Electric field control of exchange bias (EB) plays an important role in spintronics due to its attractive merit of lower energy consumption. Here, we propose a novel method for electrically tunable EB at room temperature in a device with the stack of Si/SiO 2 /Ta/Pt/Ag/Mn-doped ZnO (MZO)/Pt/FeMn/ Co/ITO by resistive switching (RS) via electrochemical metallization (ECM). The device shows enhanced and weakened EB when set at high-resistance state (HRS) and low-resistance state (LRS), respectively. For the device at LRS, the aberrationcorrected scanning transmission electron microscopy (STEM) characterizations unambiguously reveal that the Ag filaments grow initially from the Ag anode and then elongate toward the ITO cathode. It is inferred that at LRS, a small portion of Ag filaments have passed through the MZO and the intervening thin Pt layer and extended into the FeMn layer. After applying reverse voltage, these Ag filaments are electrochemically dissolved and ruptured near the MZO/Pt interface. This is considered to be the main mechanism responsible for RS and switchable EB as well. This work presents a new strategy for designing low-power, nonvolatile magnetoelectric random access memory devices.
Herein, an intriguing exchange bias (EB) effect manifesting itself from positive to negative with an increase in the cooling field (H FC ) is reported in the single crystal of Mndoped metal−organic framework (MOF) [NH 2 (CH 3 ) 2 ][Fe III Fe II (HCOO) 6 ] (1) by finely tuning the exchange interactions between the magnetic ions. Note that the doping ratio of Mn relative to the total metal ions is about 15%. Negative magnetization and EB below the compensation temperature were both observed in 1, and the EB field (H E ) changes its sign from positive to negative when H FC is larger than ∼10 kOe. The abnormal H FC dependence of EB can be interpreted explicitly by a combination of negative magnetization and couplings among the ions of Fe 3+ , Fe 2+ , and Mn 2+ with varying the H FC . This work demonstrates a tunable EB in MOFs, in favor of designing novel magnetic devices.
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