Large inverse magnetoresistance of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">CrO</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:mo>∕</mml:mo><mml:mi mathvariant="normal">Co</mml:mi></mml:mrow></mml:math>junctions with an artificial barrier

Parker, Jeffrey B.; Ivanov, P. G.; Lind, D. M.; Xiong, Peng; Xin, Yan

doi:10.1103/physrevb.69.220413

Cited by 36 publications

(17 citation statements)

References 21 publications

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“…9,10 The films are patterned into 50ϫ 200 m 2 Hall bar structures using optical lithography and wet chemical etching. For the magnetotransport experiments, the samples are mounted in a superconducting magnet system and the sample temperature is stabilized using a variable temperature insert.…”

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confidence: 99%

Planar Hall effect and magnetic anisotropy in epitaxially strained chromium dioxide thin films

Goennenwein

Keizer

Schink

et al. 2007

Applied Physics Letters

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We have measured the in-plane anisotropic magnetoresistance of 100 nm thick CrO 2 thin films at liquid He temperatures. In low magnetic fields H, both the longitudinal and the transverse ͑planar Hall͒ resistance show abrupt switches, which characteristically depend on the orientation of H. All the experimental findings consistently demonstrate that the magnetic anisotropy in these CrO 2 thin films is biaxial. We show that the biaxial magnetic anisotropy is due to epitaxial coherency strain, and that it naturally explains the complex magnetic switching behavior reported recently in Half-metallic ferromagnets ͑HMFs͒ such as chromium dioxide ͑CrO 2 ͒ are intriguing materials. 1 Their density of states is finite at the Fermi energy E F for one spin direction, while an insulating gap exists for the other. Accordingly, HMFs are 100% spin polarized at E F . This makes them very attractive for the study of spin-related transport phenomena, e.g., in magnetic tunnel junctions, 2 for the investigation of the spin-dependent decay of superconducting correlations, 3,4 or for current-induced magnetization reversal. 5 Bulk CrO 2 is usually considered as a uniaxial ferromagnet with sizeable second order uniaxial contributions, the c axis being the easy direction. [6][7][8] In contrast, the magnetic properties of CrO 2 thin films are more diverse. In CrO 2 layers grown epitaxially on ͑100͒ TiO 2 substrates, the strain resulting from the lattice mismatch makes the b axis magnetically easy for layer thicknesses d Ͻ 50 nm. 9,10 For films with 50 nmഛ d ഛ 250 nm, a more complex magnetic behavior was observed and attributed to the superposition of different easy directions because of an inhomogeneous strain distribution across the film thickness. 10 In this letter, we present anisotropic magnetoresistance ͑AMR͒ experiments, which show that the complex magnetic behavior in 100 nm thick CrO 2 films can be understood in terms of biaxial magnetic symmetry. We observe abrupt switches in the AMR, which sensitively depend on the angle enclosed between the current direction and the external, in-plane magnetic field. From the fields at which these switches take place, we conclude that the magnetic anisotropy in the film plane is biaxial. Upon taking into account the magnetic anisotropy contributions due to epitaxial coherency strain, the experimentally observed switching fields can be modeled quantitatively. This shows that crystalline strain qualitatively alters the magnetic anisotropy of CrO 2 thin films.The 100 nm thick, single crystalline CrO 2 films are grown by chemical vapor deposition on ͑100͒-oriented TiO 2 substrates. 9,10 The films are patterned into 50ϫ 200 m 2 Hall bar structures using optical lithography and wet chemical etching. For the magnetotransport experiments, the samples are mounted in a superconducting magnet system and the sample temperature is stabilized using a variable temperature insert. The magnetic field H is applied in the film plane. The angle between H and the current density j can be freely adjusted by means of...

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confidence: 99%

Planar Hall effect and magnetic anisotropy in epitaxially strained chromium dioxide thin films

Goennenwein

Keizer

Schink

et al. 2007

Applied Physics Letters

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“…(4) and (5). Meanwhile, in Mg rich limit ( μ Mg = 0 eV), the value of Γ equals −0.0469 eV/Å [2], which means this structure, corresponding B-Mg interface, is stable under Mg rich condition. It also can be observed from Fig.…”

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confidence: 92%

“…A wide variety of functional thin films grown epitaxially on different substrates have received much attention because of their importance in many technological applications [1][2][3][4][5][6][7][8]. For instances, oxide films epitaxially on metal substrates can be applied for microelectronics, catalysis, magnetic tunnel junctions, etc.…”

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confidence: 99%

“…For instances, oxide films epitaxially on metal substrates can be applied for microelectronics, catalysis, magnetic tunnel junctions, etc. [1][2][3][4][5][6], while superconductive films, such as NbN, MgB 2 and Molybdenum nitrides films, can be used for Josephson junctions due to their high transition temperature T c [7][8][9]. Motivated by the fact that MgB 2 , with simple lattice structures, has high transition temperature (T c = 39 K) [10], the MgB 2 films on various cyclostyles are fabricated and widely investigated [11][12][13][14][15][16][17] for the possible applications in nanoelectronic devices due to their unique properties.…”

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First-principles study of MgB2 film on the MgO(111) polar surface

et al. 2008

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“…[5] These properties make chromium dioxide a promising material to be used in magnetoresistive structures such as spin valves and magnetic tunnel junctions. [6][7][8] Moreover, Keizer et al [9] showed that CrO 2 could be used in magnetization-controlled Josephson junctions in which supercurrents can be switched with the direction of the magnetization, similar to spin valve transistors. Although much effort has been put into developing efficient and controlled methods for preparing CrO 2 thin films, their synthesis at moderate pressures and temperatures is a nontrivial and challenging task due to the metastability of this oxide.…”

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confidence: 98%

Influence of Growth Temperature and Carrier Flux on the Structure and Transport Properties of Highly Oriented CrO₂ on Al₂O₃ (0001)

Sousa

Dias

Conde

et al. 2007

Chemical Vapor Deposition

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Abstract:In this work we report on the structure and magnetic and electrical transport properties of CrO2 films deposited onto (0001) sapphire by atmospheric pressure (AP)CVD from a CrO3 precursor. Films are grown within a broad range of deposition temperatures, from 320 to 410 degrees C, and oxygen carrier gas flow rates of 50-500 seem, showing that it is viable to grow highly oriented a-axis CrO2 films at temperatures as low as 330 degrees C i.e., 60-70 degrees C lower than is reported in published data for the same chemical system. Depending on the experimental conditions, growth kinetic regimes dominated either by surface reaction or by masstransport mechanisms are identified. The growth of a Cr2O3 interfacial layer as an intrinsic feature of the deposition process is studied and discussed. Films synthesized at 330 degrees C keep the same high quality magnetic and transport properties as those deposited at higher temperatures. Document Type: ArticleLanguage: English

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Large inverse magnetoresistance ofCrO2∕Cojunctions with an artificial barrier

Cited by 36 publications

References 21 publications

Planar Hall effect and magnetic anisotropy in epitaxially strained chromium dioxide thin films

Planar Hall effect and magnetic anisotropy in epitaxially strained chromium dioxide thin films

First-principles study of MgB2 film on the MgO(111) polar surface

Influence of Growth Temperature and Carrier Flux on the Structure and Transport Properties of Highly Oriented CrO₂ on Al₂O₃ (0001)

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Large inverse magnetoresistance ofCrO2∕Cojunctions with an artificial barrier

Cited by 36 publications

References 21 publications

Planar Hall effect and magnetic anisotropy in epitaxially strained chromium dioxide thin films

Planar Hall effect and magnetic anisotropy in epitaxially strained chromium dioxide thin films

First-principles study of MgB2 film on the MgO(111) polar surface

Influence of Growth Temperature and Carrier Flux on the Structure and Transport Properties of Highly Oriented CrO2 on Al2O3 (0001)

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Influence of Growth Temperature and Carrier Flux on the Structure and Transport Properties of Highly Oriented CrO₂ on Al₂O₃ (0001)