Nonvolatile Control of Magnetocaloric Operating Temperature by Low

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Nonvolatile Control of Magnetocaloric Operating Temperature by Low Voltage Jiahong Wen, Xiaoyu Zhao, Qian Li, Yuanqiang Xiong, Dunhui Wang, and Youwei Du ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b03088 • Publication Date (Web): 16 Apr 2018 Downloaded from http://pubs.acs.org on April 16, 2018

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ACS Applied Materials & Interfaces

Nonvolatile Control of Magnetocaloric Operating Temperature by Low Voltage Jiahong Wen,† Xiaoyu Zhao,† Qian Li,† Yuanqiang Xiong,‡ Dunhui Wang*,† and Youwei Du† †National Laboratory of Solid State Microstructures and Jiangsu Key Laboratory for Nano technology, Nanjing University, Nanjing 210093, P.R. China ‡College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 400047, P.R. China

Abstract The limited operating temperature is the main obstacle for the practical applications of magnetic refrigeration. In this work, the voltage control of magnetocaloric effect is investigated in a La0.7Sr0.3MnO3 (LSMO)/CeO2/Pt device. Different from the conventional method of volatile manipulating MCE by large-voltage-induced-strain, nonvolatile manipulation of magnetocaloric operating temperature with good stability is realized in the LSMO film by applying low voltages of less than 2.3 V. The experimental results demonstrate that the magnetic entropy change peak temperature for the LSMO film can be extended from 302 K to 312 K by voltage. This nonvolatile effect can be well understood with the resistive switching mechanism and has potential in promoting microscale refrigeration technology. Keywords: Magnetocaloric effect, Resistive switching, Magnetoelectric effect, Voltage control of magnetism, Oxygen vacancy dynamic.

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1. Introduction Magnetic refrigeration based on magnetocaloric effect (MCE) has attracted increasing attention due to its high cooling efficiency and environmental friendliness, which is regarded as a promising candidate to replace traditional vapor-compressing refrigeration technology.1-3 For obvious reasons, the magnetic materials showing large MCE in the vicinity of room temperature are more desirable owing to their potential applications for household cooling applications. The rare earth metal gadolinium (Gd) is considered as an active magnetic refrigerant for room-temperature magnetic refrigeration since it has a large magnetic entropy change ( ∆S M ) around its Curie temperature (TC) of 294 K.4 However, the commercially application for this rare earth metal is somehow limited because of its high cost. In 1997, giant MCE (almost twice larger than that in Gd) was discovered in Gd5Si2Ge2 alloy by Pecharsky and Gschneidner, which can be regarded as a landmark event in the research of magnetic refrigeration.5 From then on, good MCE performance is reported one by one in many systems, such as perovskite manganites,6 La(Fe,Si)13,7 FeMnPAs,8 MnAs1-xSbx9 and Ni-Mn based Heusler alloys.10,11 Parallel to the development of new magnetocaloric materials, strategies to improve the MCE properties in these materials have been explored recently as well. It is known that one of the shortcomings for currently reported large MCE materials is the limited operating temperature, which is attributed to their narrow magnetic phase transition regions. In order to solve this problem, some alternative solutions are proposed. For example, it is reported that stacking a series of refrigerants with successive working temperature regions can effectively extend the 2


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refrigeration temperature region.12,13 Nevertheless, this method inevitably increases the cost and is less efficient since most of these refrigerants don’t work in a given temperature region. In addition, driving magnetic phase transition by more than one species of external stimuli is considered as a potential way to extend the working temperature region of magnetic refrigeration.14-16 For example, we have demonstrated in a magnetoelectric heterostructure, Ni44Co5.2Mn36.7In14.1/ Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN-PT), that the magnetocaloric operating temperature of the magnetic material can be tuned through piezoelectric strain arising in the substrate under electric field.17 However, this type of manipulation is usually volatile and needs a few hundred volts of voltage to apply on the piezoelectric substrate,17,18 which are disadvantageous for the practical applications. Hence finding alternative mechanism to nonvolatile control of magnetocaloric operating temperature by low voltage still remains a main challenge. Recently, many experimental or theoretical results have demonstrated that the physical properties of some oxides can be effectively manipulated through reversible redox reaction, oxygen ions migration or the chemical and valence evolutions at the metal(oxide)/oxide

interfaces.19-25 Specially,

in

some

magnetic-oxides-based

heterostructures, their magnetic properties can be tuned by voltage-induced resistive switching (RS).19,20 Furthermore, this manipulation of magnetism is nonvolatile and can be accomplished under low voltage.19,20 It is known that perovskite manganites are good candidates for magnetic refrigeration since they can exhibit large MCE.26 Therefore, it is reasonable to assume that their magnetocaloric properties are likely to 3



be tuned by voltage-triggered RS. However, in order to avoid the electric breakdown, the perovskite manganites for studying RS effect should be prepared at a low oxygen pressure to ensure a high resistivity.27,28 As a result, these oxides usually exhibit weak magnetism owing to strong coupling between their electric and magnetic properties.27 Therefore, it is difficult to achieve large MCE in these perovskite manganites due to their small magnetic moments. In this paper, a RS device of La0.7Sr0.3MnO3 (LSMO)/CeO2/Pt is prepared for investigating the voltage control of MCE in the LSMO film. In this device, the LSMO film is prepared in a high oxygen pressure which enable it to have good conductivity. Thus in this device, LSMO and Pt can act as the top and bottom electrodes, respectively. Meanwhile, this LSMO film has an ability to show strong magnetism due to low concentration of oxygen vacancies, and consequently, large MCE according to the Maxwell relation for calculating ∆S M . The reasons for choosing CeO2 as RS material are: (a) it can generate and eliminate oxygen vacancies easily by voltage-induced redox between conductive CeO2-x and non-conductive CeO2 phase and has a good ability of oxygen vacancies conducting, so the magnetic properties of LSMO can be manipulated due to the variation of oxygen vacancies;29-32 (b) It is a high k dielectric material which possesses very low leakage current at low operating voltage.33,34 So a large area of LSMO film instead of a series of LSMO point-electrodes can be deposited on CeO2 to act as the top electrodes, which is meaningful for the application. Our experimental results demonstrate that under low voltages of less than 2.3 V, the magnetic phase

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temperature can be reversibly tuned and the magnetic entropy change peak temperature is extended from 302 K to 312 K. 2. Experimental section The films of CeO2 and La0.7Sr0.3MnO3 (LSMO) were sequentially deposited on a 5 mm × 5 mm × 0.5 mm Pt/Ti/SiO2/Si substrate from the stoichiometric targets using pulsed laser deposition (PLD) with a 248 nm KrF excimer laser at 3 Hz. The base vacuum of the chamber was below 5.0×10-5 Pa. During deposition of the films, the substrate temperature was kept at 650 °C while oxygen pressure was 35 Pa. The crystal structure of the sample was characterized by X-ray diffraction (XRD) at room temperature. The thickness of the films was measured by scanning electron microscope (SEM). The electric transport properties of the LSMO/CeO2/Pt device were investigated using a Keithley 2400 current source. The magnetic properties of LSMO film was measured using a superconducting quantum interference devices magnetometer (SQUID, Quantum Design). 3. Results and discussion Figure 1a shows the cross-section SEM image of the LSMO/CeO2/Pt device. It is clear that CeO2 and LSMO films are successively deposited on the Pt electrode. The thickness of these films are estimated to be about 200 nm and 100 nm, for CeO2 and LSMO, respectively. The X-ray diffraction (XRD) pattern for the device is shown in Figure 1b. Besides the diffraction peaks from the substrate, the θ-2θ patterns are collected with (111) and (200) peaks for the CeO2 film, and (110) peak for the LSMO film, indicating that these films are polycrystalline.

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The schematic image of the device for measuring RS properties is shown in Figure 2a, in which Pt and the LSMO film act as bottom and top electrodes, respectively. Before the measurement of RS, an electroforming process with a voltage of 6 V is performed to create some oxygen vacancies, which leads to a low resistance state (LRS) of the device. Then the LSMO/CeO2/Pt device begins to switch from ON-state (the low resistance state, LRS) to OFF-state (the high resistance state, HRS) on applying a negative sweeping voltage, which is shown in Figure 2b. It is obvious that the current gradually increases and then shows a sharp drop at a reset voltage of -1.5 V, indicating that the device changes from a LRS to a HRS (reset process). A subsequent positive biasing returns the device from OFF-state back to ON-state again at a set voltage of 2.3 V, which is defined as a set process. Thus a bipolar RS behavior of the LSMO/CeO2/Pt device is observed, which is consistent with the reported results in the CeO2-based RS devices.29-32,35-38 During the electroforming and set processes, a current compliance (Icomp) of 10 mA is adopted to avoid permanent dielectric breakdown of the device. Temperature dependence of magnetization (M-T) for the LSMO film with different resistance states are measured under a magnetic field of 500 Oe. As shown in Figure 3a, three typical ferromagnetic M-T curves are observed and all the phase transitions occur just around 300 K, which is meaningful for the room-temperature magnetic refrigeration. According to the dM dT curve showing in the inset of Figure 3a, the values of TC for LR and HR states are 302 and 312 K, which is lower and larger than that of origin resistance state (ORS) of 305 K, respectively. Figure 3b shows the magnetic hysteresis loops under three resistance states at 302 K, in which typical ferromagnetic behaviors are observed. For the ORS, the saturation 6


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magnetization (MS) for as-prepared LSMO film is 28.10 emu/g. As the device is triggered to the LRS, the MS value of the LSMO film decreases to 24.36 emu/g. However, in the case of HRS, its MS significantly increases to 39.11 emu/g. The inset of Figure 3b shows the temperature dependence of Ms for three resistance states. Obviously, the MS values of the LSMO film vary with the voltage-induced resistance states, demonstrating that its magnetism can be effectively manipulated by low voltage. It is widely accepted that the bipolar RS behavior of CeO2 is ascribed to the formation and rupture of conducting filaments consisting of oxygen vacancies. 29-32,35-38

Before measuring the RS effect, an electroforming process is carried out on

the device to generate some oxygen vacancies, which contributes to form conducting filaments. As a result, the device is in a LRS, which is schematically shown in Figure 4a. As mentioned above, the generation of oxygen vacancies in CeO2 is due to the reduction reaction between CeO2 and CeO2-x.36-38 Here CeO2-x can be regarded as an oxygen reservoir,29-32 and the oxygen anions can migrate toward the top electrode under a positive voltage. Therefore, the filaments consisting of oxygen vacancies are broken, leading to a HRS, which is shown in Figure 4b. As shown in Figure 4c, when a negative voltage is applied, the oxygen vacancies will rearrange along the electric field direction and connect into conducting filaments, resulting in a LRS again. These schematic images can also be applied to understand the effect of RS behavior on the magnetic properties of the LSMO film. It is known that the ferromagnetism of the LSMO film stems from the double exchange between Mn3+ and Mn4+. So the 7



formation of Mn3+-O2−-Mn4+ chains plays a key role in determining its magnetic properties.27 When the device is in a LRS, there are plenty of oxygen vacancies in the LSMO film as showing Figure 4a and c, leading to the break of Mn3+-O2−-Mn4+ chains. As a result, a relatively low TC and little Ms are observed in LSMO film. As shown in Figure 4b, in the case of HRS, the oxygen anions migrating from CeO2-x will repair the Mn3+-O2−-Mn4+ chains, which is helpful to enhance the exchange interaction between Mn3+ and Mn4+ ions, and consequently, give rise to increased values of TC and MS. Since TC of the LSMO film can be tuned by different resistance states, it is necessary to investigate the effect of this manipulation on MCE. Figures 5a and b show a series of isothermal magnetization (M-H) curves for the LSMO film in LRS and HRS, respectively. Here a magnetic field with a maximum value of 10 k Oe is applied along the film plane. Based on these M-H curves, the values of ∆S M are calculated using Maxwell relation:21 H  ∂M (T , H )  ∆S M (T , H ) = ∫   dH . 0 ∂T  H

The temperature dependence of ∆S M for LRS and HRS is shown in Figure 6. In the case of LRS, the maximum value of ∆S M is 1.0 J/kg K and the peak temperature is 302 K. When the LSMO film is in a low-voltage-induced HRS, the maximum value of ∆S M increases to 1.2 J/kg K, which can be ascribed to its enhanced value of MS. More importantly, a remarkable increase of peak temperature of MCE, from 302 K to 312 K, is observed, indicating that the magnetocaloric operating temperature can be effectively tuned by voltage. It is reported that the materials efficiency (η) is an 8


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important parameter to evaluate the caloric performance of a materials.39 Here η can be calculated as follows:

η = QW where Q is the heat during the magnetization or the demagnetization process and W is the work to drive magnetocaloric effect which can be calculated by integrating the area enclosed by the corresponding magnetization curves and the vertical axis.39 As a result, the calculated values of η are 5.29 and 7.30 for LRS and HRS, respectively. Obviously, the values of not only ∆S M but also η are enhanced in HRS. It is reported that the CeO2-based RS devices usually have excellent reliability.35-38 In order to reflect the stability of this voltage-manipulating effect of MCE, the endurance and retention characteristics of RS behavior for the LSMO/CeO2/Pt device are investigated. Figure 7a shows the voltage pulse cycles dependence of the resistance for the device. It is obvious that two stable resistance states can be maintained up to more than 300 cycles. As shown in Figure 7b, both LRS and HRS can remain stable up to 104 s without any obvious degradation. All these results demonstrate that the RS effect in the LSMO/CeO2/Pt device is repeatable and reliable, ensuring that the magnetocaloric operating temperature can be stably and reproducibly controlled by low voltage. 4. Conclusions In conclusion, the voltage control of MCE has been investigated in a LCMO/CeO2/Pt device. By applying low voltage, the resistance state of this device can be switched between HRS and LRS, which leads to remarkable changes of Ms 9



and TC in the LSMO film. Taking advantage of this feature, nonvolatile control of magnetocaloric operating temperature is realized in this device by low voltage. Moreover, this manipulation effect has good repeatability and reliability. All these results not only provide an effective method to extend the magnetic refrigeration operating temperature region but also are available for designing next-generation voltage-tunable spintronic devices. Author information Corresponding Authors *E-mail: [email protected] Author Contributions Jiahong Wen carried out the samples preparation and most of the measurements. Jiahong Wen and Dunhui Wang designed the outline of the manuscript and wrote the main manuscript text. All authors contributed to the manuscript with discussion and revision. Notes The authors declare no competing financial interest. Acknowledgments This work is supported by the National Natural Science Foundation of China (Grant No. 51571108). References (1) Gschneidner, K. A.; Pecharsky, V. K.; Tsokol, A. O. Recent Developments in Magnetocaloric Materials. Rep. Prog. Phys. 2005, 68, 1479-1539.

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(2) Bruck, E. Developments in Magnetocaloric Refrigeration. J. Phys. D-Appl. Phys. 2005, 38, 381-391. (3) Franco, V.; Blazquez, J. S.; Ingale, B.; Conde. A. The Magnetocaloric Effect and Magnetic Refrigeration Near Room Temperature: Materials and Models. Annu. Rev. Mater. Res. 2012, 42, 305-342.

(4) Gschneidner, K. A.; Pecharsky, V. K. Magnetocaloric Materials. Annu. Rev. Mater. Sci. 2000, 30, 387-429.

(5) Pecharsky, V. K.; Gschneidner, K. A. Giant Magnetocaloric Effect in Gd5(Si2Ge2). Phys. Rev. Lett. 1997, 78, 4494-4497.

(6) Guo, Z. B.; Du, Y. W.; Zhu, J. S.; Huang, H; Ding, W. P.; Feng, D. Large Magnetic Entropy Change in Perovskite-type Manganese Oxides. Phys. Rev. Lett. 1997, 78, 1142-1145. (7) Hu, F. X.; Shen, B. G.; Sun, J. R.; Cheng, Z. H.; Rao, G. H.; Zhang, X. X. Influence of Negative Lattice Expansion and Metamagnetic Transition on Magnetic Entropy Change in the Compound LaFe11.4Si1.6. Appl. Phys. Lett. 2001, 78. 3675-3677. (8) Tegus, O.; Bruck, E.; Buschow, K. H. J.; de Boer, F. R. Transition-metal-based Magnetic Refrigerants for Room-temperature Applications. Nature 2002, 415, 150-152. (9) Wada, H.; Tanabe, Y. Giant magnetocaloric effect of MnAs1-xSbx. Appl. Phys. Lett. 2001, 79, 3302-3304.

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(10) Krenke, T.; Duman, E.; Acet, M.; Wassermann, E. F.; Moya, X.; Manosa, L.; Planes, A. Inverse Magnetocaloric Effect in Ferromagnetic Ni-Mn-Sn Alloys. Nat. Mater. 2005, 4, 450-454.

(11) Han, Z. D.; Wang, D. H.; Zhang, C. L.; Xuan, H. C.; Gu, B. X.; Du, Y. W. Low-field Inverse Magnetocaloric Effect in Ni50-xMn39+xSn11 Heusler Alloys. Appl. Phys. Lett. 2007, 90, 042507-042510.

(12) Morrison, K.; Barcza, A.; Moore, J. D.; Sandeman, K. G.; Chattopadhyay, M. K.; Roy, S. B.; Caplin, A. D.; Cohen, L. F. The Magnetocaloric Performance in Pure and Mixed Magnetic Phase CoMnSi. J. Phys. D-Appl. Phys. 2010, 43, 195001-195009. (13) Li, L. W.; Kadonaga, M.; Huo, D. X.; Qian, Z. H.; Namiki, T.; Nishimura, K. Low Field Giant Magnetocaloric Effect in RNiBC (R = Er and Gd) and Enhanced Refrigerant Capacity in its Composite Materials. Appl. Phys. Lett. 2012, 101, 122401-122404. (14) Moya, X.; Kar-Narayan, S.; Mathur, N. D. Caloric Materials Near Ferroic Phase Transitions. Nat. Mater. 2014, 13, 439-450. (15) Planes, A.; Stern-Taulats, E.; Castan, T.; Vives, E.; Manosa, L.; Saxena, A. Caloric and Multicaloric Effects in Shape Memory Alloys. Materials Today: Proceedings 2015, 2, 477-484.

(16) Crossley, S.; Mathur, N. D.; Moya, X. New Developments in Caloric Materials for Cooling Applications. AIP Advances 2015, 5, 067153-067160. (17) Gong, Y. Y.; Wang, D. H.; Cao, Q. Q.; Liu, E. K.; Liu, J.; Du, Y. W. Electric Field Control of the Magnetocaloric Effect. Adv. Mater. 2015, 27, 801-805. 12


Page 12 of 24

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(18) Hu, Q. B.; Li, J.; Wang, C. C.; Zhou, Z. J.; Cao, Q. Q.; Zhou, T. J.; Wang, D. H.; Du Y. W. Electric Field Tuning of Magnetocaloric Effect in FeRh0.96Pd0.04/PMN-PT Composite Near Room Temperature. Appl. Phys. Lett. 2017, 110, 222408-222412. (19) Chen, G.; Song, C.; Chen, C.; Gao, S.; Zeng, F.; Pan, F. Resistive Switching and Magnetic Modulation in Cobalt-Doped ZnO. Adv. Mater. 2012, 24, 3515-3520. (20) Xiong, Y. Q.; Zhou, W. P.; Li, Q.; He, M. C.; Du, J.; Cao, Q. Q.; Wang, D. H.; Du, Y. W. Electric Field Manipulation of Nonvolatile Magnetization in Au/NiO/Pt Heterostructure with Resistive Switching Effect. Appl. Phys. Lett. 2014, 105, 032410-032414. (21) Li, Y. Y.; Wang, Q. X.; An, M.; Li, K.; Wehbe, N.; Zhang, Q.; Dong, S.; Wu, T. Nanoscale Chemical and Valence Evolution at the Metal/Oxide Interface: A Case Study of Ti/SrTiO3. Adv. Mater. Interfaces 2016, 3, 1600201-1600209. (22) Guan, X. W.; Hu, W. J.; Haque, M. A.; Wei, N. N.; Liu, Z. X.; Chen, A. T.; Wu, T. Light-Responsive Ion-Redistribution-Induced Resistive Switching in Hybrid Perovskite Schottky Junctions. Adv. Funct. Mater. 2018, 28, 1704665-1704676. (23) Feng, N.; Mi, W. B.; Wang, X. C,; Cheng, Y. C.; Schwingenschlögl, U. Superior Properties of Energetically Stable La2/3Sr1/3MnO3/Tetragonal BiFeO3 Multiferroic Superlattices. ACS Appl. Mater. Interfaces 2015, 7, 10612-10616. (24) Ge, C.; Jon, K. J.; Zhang, Q. H.; Du, J. Y.; Gu, L.; Guo, H. Z.; Yang, J. T.; Gu, J. X.; He, M.; Xing, J.; Wang, C.; Lu, H. B.; Yang, G. Z. Toward Switchable Photovoltaic Effect via Tailoring Mobile Oxygen Vacancies in Perovskite Oxide Films. ACS Appl. Mater. Interfaces 2016, 8, 34590-34597. 13



(25) Bao, S. Y.; Ma, J.; Yang, T.; Chen, M. F.; Chen, J. H.; Pang, S. L.; Nan, C. W.; Chen, C. L. Oxygen Vacancy Dynamics at Room Temperature in Oxide Heterostructures. ACS Appl. Mater. Interfaces 2018, 10, 5107-5113. (26) Phan, M. H.; Yu, S. C. Review of The Magnetocaloric Effect in Manganite Materials. J. Magn. Magn. Mater. 2007, 308, 325-340. (27) Xiong, Y. Q.; Zhou, W. P.; Li, Q.; Cao, Q. Q.; Tang, T.; Wang, D. H.; Du, Y. W. Electric Field Modification of Magnetism in Au/La2/3Ba1/3MnO3/Pt Device. Sci. Rep. 2015, 5, 12766-12772. (28) Jin, K. J.; Gu, L.; Jin, Y. L.; Ge, C.; Wang, C.; Guo, H. Z.; Lu, H. B.; Zhao, R. Q.; Yang, G. Z. Evidence for a Crucial Role Played by Oxygen Vacancies in LaMnO3 Resistive Switching Memories. Small 2012, 8, 1279-1284. (29) Gao, P.; Wang, Z. Z.; Fu, W. Y.; Liao, Z. L.; Liu, K. H.; Wang, W. L.; Bai, X. D.; Wang, E. In Situ TEM Studies of Oxygen Vacancy Migration for Electrically Induced Resistance Change Effect in Cerium Oxides. Micron 2010, 41, 301-305. (30) Sun, X.; Sun, B.; Liu, L. F.; Xu, N.; Liu, X. Y.; Han, R. Q.; Kang, J. F.; Xiong, G. C.; Ma, T. P. Resistive Switching in CeOx Films for Nonvolatile Memory Application. IEEE Electron Device Lett. 2009, 30, 334-336. (31) Esch, F; Fabris, S; Zhou, L; Montini, T; Africh, C; Fornasiero, P; Comelli, G; Rosei, R. Electron Localization Determines Defect Formation on Ceria Substrates. Science 2005, 309, 752-755.

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(32) Torbrugge, S.; Reichling, M.; Ishiyama, A.; Morita, S.; Custance, O. Evidence of Subsurface Oxygen Vacancy Ordering on Reduced CeO2(111). Phys. Rev. Lett. 2007, 99, 056101-056104.

(33) Mogensen, M.; Sammes, N. M.; Tompsett, G. A. Physical, Chemical and Electrochemical Properties of Pure and Doped Ceria. Solid State Ion. 2000, 129, 63-94. (34) Skorodumova, N. V.; Simak, S. I.; Lundqvist, B. I.; Abrikosov, I. A.; Johansson, B. Quantum Origin of The Oxygen Storage Capability of Ceria. Phys. Rev. Lett. 2002, 89, 166601-166604.

(35) Ismail, M.; Ahmed, E.; Rana, A. M.; Hussain, F.; Talib, I.; Nadeem, M. Y.; Panda, D.; Shah, N. A. Improved Endurance and Resistive Switching Stability in Ceria Thin Films Due to Charge Transfer Ability of Al Dopant. ACS Appl. Mater. Interfaces 2016, 8, 6127-6136.

(36) Smail, M.; Huang, C. Y.; Panda, D.; Hung, C. J.; Tsai, T. L.; Jieng, J. H.; Lin, C. A.; Chand, U.; Rana, A.; Ahmed, E. Forming-free Bipolar Resistive Switching in Nonstoichiometric Ceria Films. Nanoscale Res. Lett. 2014, 9, 45-52. (37) Adnan, Y.; Dewei, C.; Sean, L. Oxygen Level: The Dominant of Resistive Switching Characteristics in Cerium Oxide Thin Films. J. Phys. D: Appl. Phys. 2012, 45, 355101-355106.

(38) Hsieh, C. C.; Roy, A.; Rai, A.; Chang, Y. F.; Banerjee, S. K. Characteristics and Mechanism Study of Cerium Oxide Based Random Access Memories. Appl. Phys. Lett. 2015, 106, 173108-173112. 15



(39) Moya, X.; Defay, E.; Heine, V.; Mathur, N. D. Too Cool to Work. Nat. Phys. 2015, 11, 202-205.

Figures

Figure 1.

Figure 1. (a) The cross-section SEM image of the LSMO/CeO2/Pt device. (b) XRD pattern for the device.

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Figure 2.

Figure 2. (a) Schematic image of the LSMO/CeO2/Pt device for measuring RS behavior. (b) The I-V characteristic of the device under a direct voltage sweeping mode. The arrows indicate the bias voltage sweeping direction.

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Figure 3.

Figure 3. (a) Temperature dependence of magnetization for LSMO film in different resistance states under 500 Oe. The inset shows the dM dT curve. (b) The magnetic hysteresis loops for LSMO film in three resistance states at 302 K. The inset shows the temperature dependence of Ms for three resistance states.

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Figure 4.

Figure 4. Schematic images of oxygen vacancy-formed conducting filaments depicting the switching process in LSMO/CeO2/Pt device. (a) Electroforming, (b) Reset, and (c) Set states.

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Figure 5.

Figure 5. Isothermal magnetization curves for the LSMO film in (a) LRS and (b) HRS.

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Figure 6.

Figure 6. Temperature dependence of ∆S M for the LSMO film in LRS and HRS with the magnetic field varying from 0 to 1 kOe.

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Figure 7.

Figure 7. (a) Endurance characteristics for the LSMO/CeO2/Pt device. (b) Retention property of LRS and HRS for the LSMO/CeO2/Pt device.

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Nonvolatile Control of Magnetocaloric Operating Temperature by the Resistive Switching in Low Voltage

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Nonvolatile Control of Magnetocaloric Operating Temperature by Low

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