Spin–triplet current in half metal/conical helimagnet/superconductor heterojunctions

Jin, Li-Jing; Wang, Yue; Wen, Lin; Zha, Guo-Qiao; Zhou, Shi‐Ping

doi:10.1016/j.physleta.2012.06.017

Cited by 15 publications

(9 citation statements)

References 22 publications

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“…Note that all partial derivatives in Eqs. (20) are solely with respect to the x coordinate. In other words, the original two-dimensional problem is now reduced to a quasi one-dimensional one.…”

Section: Wide Junction Limit Wf Df : Analytical Resultsmentioning

confidence: 99%

“…If we solve the Usadel equations Eqs. (20) using the boundary conditions (21) and (23), we arrive at the following solutions to the anomalous component of the Green's function:…”

Section: Wide Junction Limit Wf Df : Analytical Resultsmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9] The interplay between ferromagnetism and superconductivity at low temperatures has constituted a unique arena for researchers in condensed matter studying superconducting spintronics in the clean, diffusive and non-equilibrium regimes. [10][11][12][13][14][15][16][17][18][19][20][21] Interest in superconducting electronics involving S/F hybrids has substantially increased during the past decade due to considerable advances in nanofabrication techniques. This consequently has led to more possibilities for S/F heterostructures playing a practical role in nanoscale systems including, quantum computers and ultra-sensitive detectors.…”

Section: Introductionmentioning

confidence: 99%

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Proximity induced vortices and long-range triplet supercurrents in ferromagnetic Josephson junctions and spin valves

Alidoust

Halterman

2015

Journal of Applied Physics

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Using a spin-parameterized quasiclassical Keldysh-Usadel technique, we theoretically study supercurrent transport in several types of diffusive ferromagnetic(F )/superconducting(S) configurations with differing magnetization textures. We separate out the even-and odd-frequency components of the supercurrent within the low proximity limit and identify the relative contributions from the singlet and triplet channels. We first consider inhomogeneous one-dimensional Josephson structures consisting of a uniform bilayer magnetic S/F /F /S structure and a trilayer S/F /F /F /S configuration, in which case the outer F layers can have either a uniform or conical texture relative to the central uniform F layer. Our results demonstrate that for supercurrents flowing perpendicular to the F /F interfaces, incorporating a conical texture yields the most effective way to observe the signatures of the long-ranged spin-triplet supercurrents. We also consider three different types of finitesized two-dimensional magnetic structures subjected to an applied magnetic field normal to the junction plane: a S/F /S junction with uniform magnetization texture, and two S/F /F /S configurations with differing F /F bilayer arrangements. In one case, the F /F interface is parallel with the S/F junction interfaces while in the other case, the F /F junction is oriented perpendicular to the S/F interfaces. We then discuss the proximity vortices and corresponding spatial maps of currents inside the junctions. For the uniform S/F /S junction, we analytically calculate the magnetic field induced supercurrent and pair potential in both the narrow and wide junction regimes, thus providing insight into the variations in the Fraunhofer diffraction patterns and proximity vortices when transitioning from a wide junction to a narrow one. Our extensive computations demonstrate that the induced long-range spin-triplet supercurrents can deeply penetrate uniform F /F bilayers when spin-singlet supercurrents flow parallel to the F /F interfaces. This is in stark contrast to configurations where a spin-singlet supercurrent flows perpendicular to the F /F interfaces. We pinpoint the origin of the induced triplet and singlet correlations through spatial profiles of the decomposed total supercurrents. We find that the penetration of the long-range spin-triplet supercurrents associated with supercurrents flowing parallel to the F /F interfaces, are more pronounced when the thickness of the F strips are unequal. Lastly, if one of the S terminals is replaced with a finite-sized normal metal, we demonstrate that the corresponding experimentally accessible S/F /F /N spin valve presents an effective platform in which the predicted long-range effects can be effectively generated and probed.

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Section: Wide Junction Limit Wf Df : Analytical Resultsmentioning

confidence: 99%

“…If we solve the Usadel equations Eqs. (20) using the boundary conditions (21) and (23), we arrive at the following solutions to the anomalous component of the Green's function:…”

Section: Wide Junction Limit Wf Df : Analytical Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Proximity induced vortices and long-range triplet supercurrents in ferromagnetic Josephson junctions and spin valves

Alidoust

Halterman

2015

Journal of Applied Physics

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“…It has been experimentally [24][25][26] and theoretically [27][28][29][30] proved that Ho can convert the singlet state into spin-aligned triplet state. This conversion can open a proximity channel for singlet Cooper pairs into linear ferromagnets, resulting in T c reduction.…”

mentioning

confidence: 99%

Magnetic state controllable critical temperature in epitaxial Ho/Nb bilayers

Robinson

Bianchetti

et al. 2014

Apl Materials

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We study the magnetic properties of Ho thin films with different crystallinity (either epitaxial or non-epitaxial) and investigate their proximity effects with Nb thin films. Magnetic measurements show that epitaxial Ho has large anisotropy in two different crystal directions in contrast to non-epitaxial Ho. Transport measurements show that the superconducting transition temperature (Tc) of Nb thin films can be significantly suppressed at zero field by epitaxial Ho compared with non-epitaxial Ho. We also demonstrate a direct control over Tc by changing the magnetic states of the epitaxial Ho layer, and attribute the strong proximity effects to exchange interaction.

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“…It is worthy to note that the parallel component is conserved in transport processes of the quasiparticles. The matrix can be defined as 38 …”

Section: Methodsmentioning

confidence: 99%

Long-range superharmonic Josephson current and spin-triplet pairing correlations in a junction with ferromagnetic bilayers

Meng

et al. 2016

Sci Rep

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The long-range spin-triplet supercurrent transport is an interesting phenomenon in the superconductor/ferromagnet () heterostructure containing noncollinear magnetic domains. Here we study the long-range superharmonic Josephson current in asymmetric junctions. It is demonstrated that this current is induced by spin-triplet pairs − or + in the thick layer. The magnetic rotation of the particularly thin layer will not only modulate the amplitude of the superharmonic current but also realise the conversion between − and + . Moreover, the critical current shows an oscillatory dependence on thickness and exchange field in the layer. These effect can be used for engineering cryoelectronic devices manipulating the superharmonic current. In contrast, the critical current declines monotonically with increasing exchange field of the layer, and if the layer is converted into half-metal, the long-range supercurrent is prohibited but still exists within the entire region. This phenomenon contradicts the conventional wisdom and indicates the occurrence of spin and charge separation in present junction, which could lead to useful spintronics devices.

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Spin–triplet current in half metal/conical helimagnet/superconductor heterojunctions

Cited by 15 publications

References 22 publications

Proximity induced vortices and long-range triplet supercurrents in ferromagnetic Josephson junctions and spin valves

Proximity induced vortices and long-range triplet supercurrents in ferromagnetic Josephson junctions and spin valves

Magnetic state controllable critical temperature in epitaxial Ho/Nb bilayers

Long-range superharmonic Josephson current and spin-triplet pairing correlations in a junction with ferromagnetic bilayers

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