Electrical control of exchange bias via oxygen migration across CoO-ZnO nanocomposite barrier

Li, Q.; Shen, Yan; Xu, Jie; Li, S. D.; Zhao, Guoxia; Long, Yun‐Ze; Shen, Tingting; Zhang, K.; Zhang, J.

doi:10.1063/1.4972962

Cited by 11 publications

(12 citation statements)

References 37 publications

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“…Furthermore, lateral patterning of the EB and magnetic domain state by electrical means is demonstrated in a continuous EB film. This is an important advantage over the solid‐state ionic approaches for electrical EB control, which thus far require patterned elements . The voltage‐programming of magnetic domains in extended magnetic films provides the possibility of electrically controlled magnetophoretic devices that rely on laterally patterned artificial EB‐induced domain structures .…”

Section: Resultsmentioning

confidence: 99%

“…In this study, temperature instead of voltage was used as a control parameter. First attempts to voltage‐control EB via ionic mechanisms involve topographically patterned elements consisting of a cobalt layer in contact with a CoO x or HfO x AFM layer that exhibits resistive switching . The voltage‐dependent EB is interpreted based on a resistive switching mechanism, involving the formation and rupture of conducting filaments in the AFM and associated dynamic atomistic rearrangement of the AFM/FM interface.…”

Section: Introductionmentioning

confidence: 99%

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Nonvolatile Electric Control of Exchange Bias by a Redox Transformation of the Ferromagnetic Layer

Zehner

Huhnstock

Oswald

et al. 2019

Adv Elect Materials

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actuation devices. [1,2] The electric currentinduced switching of magnetization is one approach, but requires large spin polarized currents. For energy efficient operation, however, the involved dissipative electric currents should be minimal. The electric field control of magnetism is a promising low-power alternative, and increasing research efforts in this direction resulted in the discovery of various mechanisms in single-and two-phase multiferroics, magnetic semiconductors, and at gated metal surfaces allowing for voltage control of magnetic properties. [2,3] The exchange bias (EB), discovered decades ago, became an important property in modern thin-film magnetism, as it offers an elegant way to prepare thermally stable artificial domains and electrodes with a predefined macroscopic magnetization alignment. [4,5] The EB is manifested by a shift of the hysteresis curve of the ferromagnetic layer along the magnetic field axis and is based on a quantum mechanical exchange interaction occurring at the common interface between a thin ferromagnetic (FM) and antiferromagnetic (AFM) layer. EB thin films are extensively used to control the direction of magnetization in magnetic memories, spintronic, and magnetophoretic devices. [6] In the latter, for example, in-plane EB systems are utilized to generate artificial magnetic domain patterns and associated reconfigurable magnetic stray field landscapes, which can be used to locally guide the motion of magnetic micro-and nanoparticles. [7] Consequently, tailoring and control of EB has become a central objective in these research branches. Chemical, mechanical, thermal, and light ion bombardment-based techniques have been developed to tailor the EB, mainly by introducing irreversible material modifications at the AFM/ FM interface, for example, by changing the interface roughness or incorporating impurities. [8] The modification of the EB is not reversible for all of these methods. Moreover, most of them require an additional magnetic field and a sophisticated apparatus, such as vacuum equipment.The electric control of EB would provide an easily integrable alternative, ideally allowing for operando and reversible EB modification. Indeed, reversible control can be achieved by electric current-induced torque in the AFM layer, but Joule heating limits the energy-efficiency. [9] Alternative low power mechanisms for voltage-control of EB are therefore of great Electric manipulation of exchange bias (EB) systems is highly attractive for the development of modern spintronic and magnetophoretic devices. To date, electric control of the EB has mainly been based on multiferroic or resistive switching behavior in specific antiferromagnets, which limits the material choice and accessible EB states. In addition, the effects are mostly volatile, requiring constant voltage application. The continuous and nonvolatile tuning of the EB via electrochemical manipulation of the ferromagnetic layer is presented. In FeO x /Fe/IrMn systems, large changes in the EB field of fully shifted magneti...

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nonvolatile Electric Control of Exchange Bias by a Redox Transformation of the Ferromagnetic Layer

Zehner

Huhnstock

Oswald

et al. 2019

Adv Elect Materials

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“…Also visible is the reduced Co/O ratio at LRS. These features suggest that a part of oxygen ions in the CoO x layer drifts toward the Co layer and then is absorbed by electrochemical process, when applying positive voltage on the bottom electrode . The enhanced Co/O ratio in the CoO x layer at LRS, corresponding to the sputtering time of 20–25 min, also reflects the formation of oxygen vacancies, which constitutes the conductive filaments.…”

mentioning

confidence: 95%

“…Resistive random access memory (RRAM), which shows low and high resistance states (LRS and HRS) by the formation and rupture of conductive filaments in metal/insulator/metal sandwich structure, is supposed to be one of promising candidates for the next‐generation nonvolatile memories . Recently, the reversible control of magnetism in resistive switching (RS) structure with magnetic storage medium has been extensively explored . The spin transport is switched ON/OFF when the RRAM is at low/high resistance states .…”

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confidence: 99%

Local Control of Exchange Bias by Resistive Switching

Wang

Sun

Zhou

et al. 2018

Physica Rapid Research Ltrs

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The local modulation of exchange bias in resistive switching structure Co/CoOx/HfOx/Pt is reported, where CoOx/HfOx serves as the storage medium and Co behaves as the bottom (positive) electrode. The stack shows the exchange bias effect for the coupling at the Co/CoOx interface at the high resistance state. The formation of metallic Co or Co‐rich CoOx conductive filaments in the CoOx layer at the low resistance state leads to the bi‐hysteresis loops, reflecting the manipulation of exchange bias at local positions, where the formation of Co‐based filaments and the Co layer just below the filaments have no pinning effect. Besides, an oxidation–reduction process occurs in the Co layer, producing the reversible variation of saturated magnetization for the high/low resistance states. The electrochemical mechanism accounts for both local manipulation of exchange bias and changeable saturated magnetization. This work provides a different avenue for designable memories and magneto‐electric coupling devices.

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“…Among various non-volatile memristance materials, transition metal oxides such as NiO, Fe 2 O 3 and CoO have been widely studied due to their high resistance ratio between the high and the low resistance states, simple constituents and compatibility with complementary metal-oxide semiconductor [19–21]. In addition, the RS in these materials is generally caused by the migration of ions [22,23]. This process is suitable for mimicking the internal dynamics of the synaptic weight change, which is also related to the migration of ions between pre- and post-synaptic neurons [24,25].…”

Section: Introductionmentioning

confidence: 99%

Synaptic memory devices from CoO/Nb:SrTiO ₃ junction

Zhao

Shang

et al. 2019

R. Soc. open sci.

Self Cite

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Non-volatile memristors are promising for future hardware-based neurocomputation application because they are capable of emulating biological synaptic functions. Various material strategies have been studied to pursue better device performance, such as lower energy cost, better biological plausibility, etc. In this work, we show a novel design for non-volatile memristor based on CoO/Nb:SrTiO 3 heterojunction. We found the memristor intrinsically exhibited resistivity switching behaviours, which can be ascribed to the migration of oxygen vacancies and charge trapping and detrapping at the heterojunction interface. The carrier trapping/detrapping level can be finely adjusted by regulating voltage amplitudes. Gradual conductance modulation can therefore be realized by using proper voltage pulse stimulations. And the spike-timing-dependent plasticity, an important Hebbian learning rule, has been implemented in the device. Our results indicate the possibility of achieving artificial synapses with CoO/Nb:SrTiO 3 heterojunction. Compared with filamentary type of the synaptic device, our device has the potential to reduce energy consumption, realize large-scale neuromorphic system and work more reliably, since no structural distortion occurs.

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Electrical control of exchange bias via oxygen migration across CoO-ZnO nanocomposite barrier

Cited by 11 publications

References 37 publications

Nonvolatile Electric Control of Exchange Bias by a Redox Transformation of the Ferromagnetic Layer

Nonvolatile Electric Control of Exchange Bias by a Redox Transformation of the Ferromagnetic Layer

Local Control of Exchange Bias by Resistive Switching

Synaptic memory devices from CoO/Nb:SrTiO ₃ junction

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Electrical control of exchange bias via oxygen migration across CoO-ZnO nanocomposite barrier

Cited by 11 publications

References 37 publications

Nonvolatile Electric Control of Exchange Bias by a Redox Transformation of the Ferromagnetic Layer

Nonvolatile Electric Control of Exchange Bias by a Redox Transformation of the Ferromagnetic Layer

Local Control of Exchange Bias by Resistive Switching

Synaptic memory devices from CoO/Nb:SrTiO 3 junction

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Product

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Synaptic memory devices from CoO/Nb:SrTiO ₃ junction