Bias dependent inversion of tunneling magnetoresistance in Fe∕GaAs∕Fe tunnel junctions

Moser, Jürgen; Zenger, Marcus; Gerl, Christian; Schuh, Dieter; Meier, Robert J.; Chen, PeiFeng; Bayreuther, G.; Wegscheider, Werner; Weiss, Dieter; Lai, Chun‐Liang; Huang, Rao; Košuth, M.; Ebert, H.

doi:10.1063/1.2364163

Cited by 52 publications

(55 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Some theories predict very large tunnel magnetoresistance: the electronic-structure of the zincblende crystal makes 'coherent tunnelling' across the Fe/GaAs(001) interface possible 16 . Moser et al fabricated Fe/GaAs/Fe(001) devices and find magnetoresistance around 6 % at 4.2 K, which reverses sign with increasing bias 17 : a result somewhat short of the 1000s of % change predicted. However, more recent theoretical work by Autès et al has demonstrated that, due to the strong spin-orbit coupling in GaAs, saturation of the magnetoresistance is reached with increasing GaAs thickness, and a limited magnetoresistance (in the range as low as 30-50 %) results 18 .…”

Section: Introductionmentioning

confidence: 98%

Interface Magnetism in Ferromagnetic Metal–compound Semiconductor Hybrid Structures

Hindmarch

2011

SPIN

View full text Add to dashboard Cite

Interfaces between dissimilar materials present a wide range of fascinating physical phenomena. When a nanoscale thin-film of a ferromagnetic metal is deposited in intimate contact with a compound semiconductor, the properties of the interface exhibit a wealth of novel behavior, having immense potential for technological application, and being of great interest from the perspective of fundamental physics. This article presents a review of recent advances in the field of interface magnetism in (001)-oriented ferromagnetic metal/III–V compound semiconductor hybrid structures. Until relatively recently, the majority of research in this area continued to concentrate almost exclusively on the prototypical epitaxial Fe / GaAs (001) system: now, a significant proportion of work has branched out from this theme, including ferromagnetic metal alloys, and other III–V compound semiconductors. After a general overview of the topic, and a review of the more recent literature, we discuss recent results where advances have been made in our understanding of the physics underpinning magnetic anisotropy in these systems: tailoring the terms contributing to the angular-dependent free-energy density by employing novel fabrication methods and ferromagnetic metal electrodes.

show abstract

Section: Introductionmentioning

confidence: 98%

Interface Magnetism in Ferromagnetic Metal–compound Semiconductor Hybrid Structures

Hindmarch

2011

SPIN

View full text Add to dashboard Cite

show abstract

“…The 13 nm thick epitaxial iron layer was grown on an 8 nm thin GaAs (001) barrier by transferring the freshly grown GaAs heterojunction from the molecular beam epitaxy chamber to a magnetron sputtering system without breaking the ultrahigh vacuum (UHV). The quality of the interface of a sample from the same wafer was checked by high-resolution transmission electron microscopy [5]. The Fe layer was covered by 50 nm cobalt and 100 nm gold which serves as back contact.…”

mentioning

confidence: 99%

“…The barrier heights can depend on the preparation technics [6] and were assumed to be 0.75 eV on each side, which was found for the Fe/GaAs interface [7]. Hence the GaAs layer constitutes a nearly rectangular barrier allowing, e.g., observation of the TMR [5,7]. In total, four batches of samples which differ in the preparation of the Au layer (with and without H + -plasma etching step, see e.g.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Tunneling Anisotropic Magnetoresistance and Spin-Orbit Coupling inFe/GaAs/AuTunnel Junctions

Moser

Matos-Abiague²,

Schuh³

et al. 2007

Phys. Rev. Lett.

Self Cite

189

268

View full text Add to dashboard Cite

We report the observation of tunneling anisotropic magnetoresistance effect (TAMR) in the epitaxial metal-semiconductor system Fe/GaAs/Au. The observed two-fold anisotropy of the resistance can be switched by reversing the bias voltage, suggesting that the effect originates from the interference of the spin-orbit coupling at the interfaces. Corresponding model calculations reproduce the experimental findings very well. PACS numbers: 73.43.Jn, 72.25.Dc, 73.43.Qt Tunneling magnetoresistance (TMR) devices consist of a tunneling barrier, typically an oxide, sandwiched between two ferromagnetic layers of different coercive fields. Such systems find widespread use in sensor and memory application as they exhibit a large resistance difference for parallel and antiparallel alignment of the ferromagnets' magnetization [1]. The TMR effect relies, within the simplest model [2], on the different spin polarizations at the Fermi energy E F in the ferromagnets; it is absent if one ferromagnetic layer is replaced by a normal metal. Hence it came as a surprise that a spin-valve-like tunnel magnetoresistance was found in (Ga,Mn)As/alumina/Au sandwiches [3]. The origin of the effect, labeled tunneling anisotropic magnetoresistance (TAMR), was associated with the anisotropic density of states in the ferromagnet (Ga,Mn)As. An enhanced anisotropic magnetoresistance (AMR) effect measured across a constriction in a (Ga,Mn)As film was ascribed to the TAMR effect, too [4]. In both experiments the fourfold symmetry, expected if the (Ga,Mn)As hole density of states is involved, was broken and ascribed to strain in (Ga,Mn)As.Here we show that a TAMR effect can also be observed in sandwiches involving a conventional ferromagnet like iron. A stack of Fe, GaAs and Au, with iron grown epitaxially on the GaAs tunneling barrier, shows pronounced spin-valve-like signatures. We observe a uniaxial anisotropy of the tunneling magnetoresistance. Depending on the bias voltage the high resistance state is either observed for the magnetization M oriented in [110] or in [110] direction. We propose a theoretical model in which the C 2v symmetry, resulting from the interference of Bychkov-Rashba and Dresselhaus spin-orbit interactions, is transferred to the tunneling probability, giving rise to the observed two-fold symmetry.A sketch of the system is shown in Fig. 1(a). The 13 nm thick epitaxial iron layer was grown on an 8 nm thin GaAs (001) barrier by transferring the freshly grown GaAs heterojunction from the molecular beam epitaxy chamber to a magnetron sputtering system without breaking the ultrahigh vacuum (UHV). The quality of the interface of a sample from the same wafer was checked by high-resolution transmission electron microscopy [5]. The Fe layer was covered by 50 nm cobalt and 100 nm gold which serves as back contact. The wafer then was glued upside down to another substrate and the original substrate was etched away. Finally, the circular, 150 nm thick top gold contact was made by employing optical lithography, selective etching of AlGa...

show abstract

“…In that case, establishing a method to keep the MR ratio high, e.g., the use of highly spin-polarized ferromagnetic electrodes, is essential. In fact, such an example has recently been reported by Kasai et al 12 Finally, let us discuss the reason why only low MR ratios have been observed in the GaAs-and ZnSe-based MTJs, 15,16,30 as opposed to the CIGS-based MTJ. To this end, we calculated MR ratios of Fe/GaAs/Fe and Fe/ZnSe/Fe MTJs using supercells with 17 barrier layers and 3 Fe layers on both sides of the barrier.…”

mentioning

confidence: 81%

First-principles study on magnetic tunneling junctions with semiconducting CuInSe₂and CuGaSe₂barriers

Masuda

Miura

2017

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

We theoretically investigate two magnetic tunneling junctions (MTJs) with different semiconductor barriers, CuInSe 2 (CIS) and CuGaSe 2 (CGS), sandwiched between Fe electrodes. We find that ∆ 1 wave functions provide dominant contributions to spin-dependent tunneling transport in both CIS-and CGS-based MTJs.We also find that the CGS-based MTJ has a much higher magnetoresistive (MR) ratio than the CIS-based MTJ, which indicates that a higher MR ratio is expected for a higher Ga concentration x in the recently reported CuIn 1−x Ga x Se 2 -based MTJs. Furthermore, we show that the CIS-and CGS-based MTJs have much smaller resistance-area products (RA) than the conventional MgO-based MTJs.Magnetoresistive (MR) devices with high MR ratios and small resistance-area products (RA) are required for realizing read sensors of ultrahigh-density hard disk drives and Gbitclass spin transfer torque magnetoresistive random access memories (STT-MRAMs). Various attempts have been made to reduce the RA of MgO-based magnetic tunneling junctions (MTJs) 1, 2 to less than 1 Ω µm 2 while keeping high tunneling magnetoresistance (TMR) ratios. Elaborate techniques to deposit ultrathin MgO barriers (∼1 nm) have been established, [3][4][5] enabling the reduction in RA to ∼1 Ω µm 2 while keeping the high MR ratio of around 200% at room temperature. On the other hand, the use of half-metallic Co-based Heusler alloys as ferromagnetic (FM) electrodes increased the MR ratio in small-RA current-perpendicular-toplane giant magnetoresistive (CPP-GMR) devices. [6][7][8][9][10][11] The highest MR ratio reported so far is 82% at room temperature for the Co 2 FeGa 0.5 Ge 0.5 /Ag/Co 2 FeGa 0.5 Ge 0.5 system with RA of ∼40 mΩ µm 2 . 11 However, this RA value is too small to obtain sufficiently high voltage output *

show abstract

Bias dependent inversion of tunneling magnetoresistance in Fe∕GaAs∕Fe tunnel junctions

Cited by 52 publications

References 27 publications

Interface Magnetism in Ferromagnetic Metal–compound Semiconductor Hybrid Structures

Interface Magnetism in Ferromagnetic Metal–compound Semiconductor Hybrid Structures

Tunneling Anisotropic Magnetoresistance and Spin-Orbit Coupling inFe/GaAs/AuTunnel Junctions

First-principles study on magnetic tunneling junctions with semiconducting CuInSe₂and CuGaSe₂barriers

Contact Info

Product

Resources

About

Bias dependent inversion of tunneling magnetoresistance in Fe∕GaAs∕Fe tunnel junctions

Cited by 52 publications

References 27 publications

Interface Magnetism in Ferromagnetic Metal–compound Semiconductor Hybrid Structures

Interface Magnetism in Ferromagnetic Metal–compound Semiconductor Hybrid Structures

Tunneling Anisotropic Magnetoresistance and Spin-Orbit Coupling inFe/GaAs/AuTunnel Junctions

First-principles study on magnetic tunneling junctions with semiconducting CuInSe2and CuGaSe2barriers

Contact Info

Product

Resources

About

First-principles study on magnetic tunneling junctions with semiconducting CuInSe₂and CuGaSe₂barriers