Giant room-temperature magnetoresistance in single-crystal Fe/MgO/Fe magnetic tunnel junctions

Yuasa, Shinji; Nagahama, Taro; Fukushima, Akio; Suzuki, Y.; Ando, Koji

doi:10.1038/nmat1257

Cited by 2,964 publications

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“…These junctions exhibited a TMR of a up to 8 % at room temperature and were used for further experiments. (Giant TMR values at room temperature [2,82] result from a symmetrydependent filtering of electrons which is found in MgO(001) barriers in combination with bcc-ordered electrodes [83].) The other MTJs had clearly different resistances or a shorted pillar and did not 6.2 TMR measurements of Fe/MgO/Ni/Cu(100) tunnel junctions show a TMR effect at all.…”

Section: Magnetoresistance Curves Of Fe/mgo/ni/cu(100) Tunnel Junctionsmentioning

confidence: 99%

“…As is well known, magnetic memory technology experienced an unprecedented rise which is still not finished. Although new developments took place on the field of reading heads which culminated in the application of large room temperature TMR sensors [1,2], the working principle of how a magnetic bit is written basically has not changed: a current flows through a coil, thus magnetizing its ferromagnetic core which in turn magnetizes the bit to be written. Following this technique, new hard disks with higher storage density were developed by simply scaling down the dimensions of all parts.…”

Section: Introductionmentioning

confidence: 99%

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Magnetoelectric coupling at metal surfaces

et al. 2010

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Section: Magnetoresistance Curves Of Fe/mgo/ni/cu(100) Tunnel Junctionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Magnetoelectric coupling at metal surfaces

et al. 2010

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“…An important device merit is the TMR ratio and much theoretical and experimental efforts have been devoted to create MTJs with different ferromagnetic metals and insulating materials in order to generate a large ratio. While materials such as MgO and Al 2 O 3 are the most popular barrier materials in practical MTJs, [16][17][18][19][20] 2D materials graphene 21,22 and transition-metal dichalcogenides 23,24 have also been investigated in this context.…”

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confidence: 99%

Nonequilibrium spin injection in monolayer black phosphorus

Chen

Wang

et al. 2016

Phys. Chem. Chem. Phys.

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Monolayer black phosphorus (MBP) is an interesting emerging electronic material with a direct band gap and relatively high carrier mobility. In this work we report a theoretical investigation of nonequilibrium spin injection and spin-polarized quantum transport in MBP from ferromagnetic Ni contacts, in two-dimensional magnetic tunneling structures. We investigate physical properties of the spin injection efficiency, the tunnel magnetoresistance ratio, spin-polarized currents, charge currents and transmission coefficients as a function of external bias voltage, for two different device contact structures where MBP is contacted by Ni(111) and by Ni(100). While both structures are predicted to give respectable spin-polarized quantum transport, the Ni(100)/MBP/Ni(100) trilayer has the superior property where the spin injection and magnetoresistance ratio maintains almost a constant value against the bias voltage. The nonequilibrium quantum transport phenomenon is understood by analyzing the transmission spectrum at nonequilibrium. PACS numbers: 72.25.Mk, 73.43.Qt Two dimensional (2D) materials have received extensive investigations in recent years for possible applications in logic devices, photonic systems, solar cells, transparent substrates and perhaps most interestingly, flexible and wearable consumer electronics. 1 The thin layer of 2D material makes it a natural choice for producing flexible structures due to their out of plane flexibility. Many 2D materials have strong covalent bonds and diverse electronic structures -properties which are needed for reliable and durable applications.So far, several 2D materials have been fabricated successfully including the celebrated graphene, 2-5 various 2D transition-metal dichalcogenides, 6-8 and the monolayer black phosphorus (MBP). [9][10][11][12][13] In particular, as one of the newest members of 2D material family, MBP is very interesting in several aspects. First, different from transition-metal dichalcogenides, black phosphorus is made of a single atomic specie, phosphorus. Second, different from graphene, the phosphorus atoms in MBP are not all located in a plane but form a buckled hexagonal structure by covalence bonds and few-layer black phosphorus has an ideal direct bandgap, a property that is very important for optoelectronics. Third, MBP has an intrinsic band gap and graphene does not. Though lower than that of graphene, few-layer black phosphorus has respectable mobilities of ∼ 1000cm 2 V −1 s −1 as reported experimentally. 9 While the materials properties make MBP very interesting and potentially important for emerging flexible electronics, another critical issue is to achieve low power operation. In this regard, one notes that the energy scale of spin dynamics is typically many orders of magnitude smaller than that of charge dynamics, and low power electronics operation can thus be achieved in spintronics devices whose operation principle is based on spin dynamics. 14,15 Existing and well studied spintronic systems include magnetic random access memory...

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“…3a and 3b has the same sign with the former DV EH, normal (V el v0), which means that the Dm th produced by the thermal spin injection has the same sign as the Dm el induced by the electrical spin injection. Given the positive TSP of epitaxial bcc FM/MgO(001) tunnel interfaces 31,32 , the Dm th induced by the SST for T Ge wT CoFe corresponds to the majority spin accumulation (Dmw0) in the Ge. This is in agreement with the expected Dm th from the SST mechanism 20 : when the TSP of FM/ oxide/SC contacts (with positive sign) is constant below E F but decay above E F , as shown in Figs.…”

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confidence: 99%

“…1a and 1b). We have calculated that the induced Dm th is (z)0.26 meV with the maximum P heating (667 nW mm 23 ) from Dm th~( {2e)DV TH =c 3,5,20 , using the measured DV TH, normal of (-)0.09 mV and the assumed TSP (c) of (1)0.7 for the epitaxial CoFe/MgO tunnel interface 31,32 . This value should be considered as a lower limit for the Dm th , since we used the highest value of TSP.…”

mentioning

confidence: 99%

Thermal Spin Injection and Accumulation in CoFe/MgO/n-type Ge Contacts

Jeon¹,

Min²,

Park³

et al. 2013

Extended Abstracts of the 2013 International Conference on Solid State Devices and Materials

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Understanding the interplay between spin and heat is a fundamental and intriguing subject. Here we report thermal spin injection and accumulation in CoFe/MgO/n-type Ge contacts with an asymmetry of tunnel spin polarization. Using local heating of electrodes by laser beam or electrical current, the thermally-induced spin accumulation is observed for both polarities of the temperature gradient across the tunnel contact. We observe that the magnitude of thermally injected spin signal scales linearly with the power of local heating of electrodes, and its sign is reversed as we invert the temperature gradient. A large Hanle magnetothermopower (HMTP) of about 7.0% and the Seebeck spin tunneling coefficient of larger than 0.74 meV K 21 are obtained at room temperature.T he tremendous power consumption and accompanying heat generation in current electronic devices requires alternative technologies to provide a solution for the energy issues and to realize the energy efficient electronics. Spintronics is a viable route for it, using the spin degree of freedom in addition to the conventional charge transport 1 . Recently another important ingredient, namely heat, appears on the stage. It has been reported that the temperature gradient and heat flow in ferromagnetic structures gives rise to a variety of spin related phenomena 2 . Understanding the interplay between heat and spin transport is a fundamental and intriguing subject but also offers unique possibilities for emerging electronics based on the combination of thermoelectrics and spintronics.Especially in SC-based spintronics, the functional use of heat provides a new route to inject and control of spin in semiconductors (SCs) 3 . The generation of non-equilibrium spin populations (i.e. spin accumulation) in nonmagnetic SC is a central issue of SC-based spintronics 1,3-5 . Significant progress has been made on the spin accumulation in various SC systems by means of circularly polarized light 4,6 , spin-polarized tunneling 7-13 , hotelectron spin filtering 14,15 , spin-orbit interaction 16,17 , or magnetization dynamics 18,19 .Intriguingly, Le Breton et al. 20 have reported a rather different mechanism for the spin accumulation, in which temperature difference across a ferromagnet (FM)/oxide/SC tunnel contact can induce the spin accumulation (Dm) in SC via Seebeck spin tunneling (SST). It was found that the SST effect, involving thermal transfer of spin angular momentum from FM to SC without a tunneling charge current, is a purely interface-related phenomenon of the tunnel contact and governed by the energy dependence of its tunnel spin polarization (TSP) 20 . This provides a conceptually new mechanism for the generation of Dm in SC as well as for the functional use of heat in spintronic devices 20 . The SST and thermal spin accumulation (Dm th ) in p-type SC (e.g., p-type Si) have been intensely studied, using a Ni 80 Fe 20 /Al 2 O 3 /SiO 2 /p-SC contact with the asymmetry in TSP of tunneling holes 20 . However, the counterpart of n-type SC still needs to be explored...

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Giant room-temperature magnetoresistance in single-crystal Fe/MgO/Fe magnetic tunnel junctions

Cited by 2,964 publications

References 22 publications

Magnetoelectric coupling at metal surfaces

Magnetoelectric coupling at metal surfaces

Nonequilibrium spin injection in monolayer black phosphorus

Thermal Spin Injection and Accumulation in CoFe/MgO/n-type Ge Contacts

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