In this work, we report direct as well as pulsed electric field-induced resistivity switching and its relaxation in a multiferroic insulator La2NiMnO6. At a fixed base temperature (Tb), the dc resistivity switches abruptly from a high to a low value, which is manifested as an upward jump in the dc current density (J) when the electric field (E) exceeds a threshold value Eth. The fractional change in the resistance is as much as 70 % at room temperature for Eth = 95 V/cm. The Eth increases with lowering Tb and follows the relation Eth(Tb) = Eth(0)exp[-Tb/T0], as similar to the behavior found in charge density wave systems. It is shown that the abrupt jump in J vanishes under pulsed electric fields if the period between pulses is long enough. Surprisingly, a step-like increase in J also occurs at a fixed dc electric field (Ec) and T = Tb, above a threshold waiting time (tth). The tth decreases with increasing Ec and Tb. Simultaneous measurement of surface temperature during the J-E sweep and temporal studies suggest that conductive channels are created in an insulating matrix due to the local self heating, and the coalescence of these channels above a threshold E- field or time causes the observed anomalies in J. However, the dissipated Joule power (P = Ith2R) at the transition from high to low resistive state in the sample decreases with lowering temperature, which suggests that the Joule heating is the consequence of transition from the high to low resistance state rather than itself a driving force of the non linear electrical transport. In addition, non linear J-E characteristics is also found even with a pulsed voltage sweep, which suggests that intrinsic mechanisms other than self heating is still active in this material.
Colossal electroresistance and colossal magnetoresistive step in paramagnetic insulating phase of single crystalline bilayered manganite(La$_{0.4}$Pr$_{0.6}$)$_{1.2}$Sr$_{1.8}$Mn$_{2}$O$_{7}$
我们报告了在（La $_{0.4}$ Pr $_{0.6}$）$_{1.2}$ Sr $_{1.8}$ Mn $_{2}$ O $_{7}$的顺磁绝缘（PMI）状态下在$ab$ -平面上施加电流引起的低温电阻的显著降低。在较低的温度下观察到一个巨大的电阻效应，达到~ 95%。在低于10 K的低温下，在5 T附近出现一个巨大的磁阻阶跃，并伴随着绝缘体-金属转变的超尖锐宽度。向晶体注入更高的电流会导致阶跃跃迁消失。这些发现与研究晶体的PMI矩阵内钉扎的短程电荷有序簇的存在有密切的关系。
Colossal electroresistance effect around room temperature in LuFe2O4
在室温附近的过渡金属氧化物LuFe 2 O 4中观察到巨大的电阻效应。在不同外加电压下的电阻测量以及高度非线性的电流-电压特性表明，小的电场能够驱动材料从绝缘状态到金属状态。绝缘-金属转变发生的阈值场随温度的升高呈指数下降。我们解释这种转变的后果，由施加的电场，这是支持在一个小的电场中的戏剧性的介电响应触发的电荷有序状态的击穿。这种巨大的电阻效应以及在室温附近的高介电可调性，在低的应用领域，使LuFe 2 O 4的许多应用非常有前途的材料。
We report a giant, ~22%, electroresistance modulation for a metallic alloy above room temperature. It is achieved by a small electric field of 2 kV/cm via piezoelectric strain-mediated magnetoelectric coupling and the resulting magnetic phase transition in epitaxial FeRh/BaTiO3 heterostructures. This work presents detailed experimental evidence for an isothermal magnetic phase transition driven by tetragonality modulation in FeRh thin films, which is in contrast to the large volume expansion in the conventional temperature-driven magnetic phase transition in FeRh. Moreover, all the experimenta…
Colossal Type-II Multiferroic Polarization Driven by Collinear Spin Orders
Nanjing University of Science and Technology（南京理工大学）；School of Physics, Nanjing University（南京大学物理学院）；Collaborative Innovation Center of Advanced Microstructures, Nanjing University（南京大学先进微结构协同创新中心）；Hefei National Laboratory（合肥国家实验室）；Jiangsu Physical Science Research Center, Nanjing University（南京大学江苏省物理科学研究中心）
Metal-insulator transition and electroresistance in lanthanum/calcium manganites La_<1-x>Ca_<x>MnO_<3> (x = 0-0.5) from voltage-current-temperature surfaces
Colossal magnon-phonon coupling in multiferroic Eu$_{0.75}$Y$_{0.25}$MnO$_3$
本文报道了Eu $_{0.75}$ Y $_{0.25}$ MnO $_3$的变温远红外光谱（10-250 cm $^{-1}$）的磁诱导电偶极吸收谱。这些光谱只发生在$e||a$极化中，由两个相对窄的电磁子特征和一个宽的吸收带组成，其中电磁子特征在$T_{FE}=30$ K开始，而吸收带在远高于$T_N=47$ K的温度下持续存在。所观察到的激发占步的静态介电常数在铁电相。观测到80 cm $^{-1}$处的电磁振子与附近的最低光学声子强耦合，该声子将其光谱重量的1/2以上转移到磁振子。我们把宽背景吸收的起因归结为声子的两个磁振子发射衰变过程。
Organic multiferroic tunnel junctions (OMFTJs) with multi-resistance states have been proposed and drawn intensive interests due to their potential applications, for examples of memristor and spintronics based synapse devices. The ferroelectric control of spin-polarization at ferromagnet (FM)/ferroelectric organic (FE-Org) interface by electrically switching the ferroelectric polarization of the FE-Org has been recently realized. However, there is still a lack of understanding of the transport properties in OMFTJs, especially the interplay between the ferroelectric domain structure in the orga…
In this work, we have designed obtained a novel multiferroic nanocomposite using the high-pressure torsion (HPT) method. The crystal structure, phase composition, morphology, ferromagnetic (FM) and ferroelectric (FE) properties of the initial powders and "multiferroic-ferromagnetic" nanocomposites have been studied comprehensively. The initial powders and their composites show the perovskite and spinel crystalline phases for the FE and FM fractions, respectively. After HPT, the particle sizes of the initial powders are decreased significantly. It is shown that the novel nanocomposite consists …
Above room temperature multiferroic tunnel junction with the altermagnetic metal CrSb
Huazhong University of Science and Technology（华中科技大学）；Florida State University（佛罗里达州立大学）；National High Magnetic Field Laboratory（国家强磁场实验室）；Charles University（查理大学）
Solid state-refrigerants have generated worldwide interest owing to their growing potential for use in efficient and green cooling devices. Caloric effects could be obtained by manipulating their degrees of freedom such as magnetization, electric polarization and volume using a variable external field. In conventional magnetocaloric refrigeration systems, the magnetocaloric effect is exploited by moving the active material in and out of the magnetic field source. Here we demonstrate that a giant and reversible magnetocaloric effect can be generated simply by rotating the multiferroic TbMn2O5 s…
Spintronic devices based on antiferromagnetic (AFM) materials hold the promise of fast switching speeds and robustness against magnetic fields. Different device concepts have been predicted and experimentally demonstrated, such as low-temperature AFM tunnel junctions that operate as spin-valves, or room-temperature AFM memory, for which either thermal heating in combination with magnetic fields, or Néel spin-orbit torque is used for the information writing process. On the other hand, piezoelectric materials were employed to control magnetism by electric fields in multiferroic heterostructures,…
