Theory of tunneling spectroscopy of normal metal/ferromagnet/spin-triplet superconductor junctions

Olthof, L. A. B. Olde; Suzuki, Shu-Ichiro; Golubov, A. A.; Kunieda, M.; Yonezawa, Suguru; Maeno, Y.; Tanaka, Yukio

doi:10.1103/physrevb.98.014508

Cited by 9 publications

(11 citation statements)

References 78 publications

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“…To understand the nature of the induced minigap, we calculate the differential conductance of a Normalmetal(N)/Insulator(I)/F/TSC junction based on a recent theoretical model [37]. This model was developed particularly for Au/SRO113/SRO214 junctions, but can be applied to our system by considering that the barrier heights Z 1 and Z 2 correspond to the Au/STO/SRO113 and SRO113/SRO214 interfaces, respectively.…”

Section: Resultsmentioning

confidence: 99%

Observation of superconducting gap spectra of long-range proximity effect in Au/SrTiO3/SrRuO3/Sr2RuO4 tunnel junctions

et al. 2019

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We observe an unconventional superconducting minigap induced into a ferromagnet SrRuO3 from a spin-triplet superconductor Sr2RuO4 using a Au/SrTiO3/SrRuO3/Sr2RuO4 tunnel junction. Voltage bias differential conductance of the tunnel junctions exhibits V-shaped gap features around zero bias, corresponding to a decrease in the density-of-states with an opening of a superconducting minigap in SrRuO3. Observation of a minigap at a surface of a 15 nm thick SrRuO3 layers confirms the spin-triplet nature of induced superconductivity. The shape and temperature dependence of the gap features in the differential conductance indicate that the even-frequency p-wave correlations dominate, over odd-frequency s-wave correlations. Theoretical calculations support this p-wave scenario. Our work provides the density-of-states proof for p-wave Cooper pair penetration in a ferromagnet and significantly put forward our understanding of the p-wave spin-triplet proximity effect between spin-triplet superconductors and ferromagnets.

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Section: Resultsmentioning

confidence: 99%

Observation of superconducting gap spectra of long-range proximity effect in Au/SrTiO3/SrRuO3/Sr2RuO4 tunnel junctions

et al. 2019

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“…Until recently, the most promising candidate had been the chiral p-wave (i.e., p x + ip ywave) pairing 4 , which is spin-triplet with broken timereversal symmetry (TRS). The spin-triplet pairing was widely accepted since it is consistent with a variety of experiments such as polarized-neutron-scatterings 5 , halfquantum vortices 6,7 , the transport measurements [8][9][10][11][12][13][14][15] , and in particular the nuclear-magnetic-resonance (NMR) measurement 16 . There were also a number of theoretical studies supporting the spin-triplet scenario [17][18][19][20][21][22][23][24] .…”

Section: Introductionmentioning

confidence: 83%

“…3(a) and 3(b) and cylindrical in Fig. 3(c), where the effective mass 15 is respectively set to ( mx , my , mz ) = (1.0, 1.0, 1.0) and (1.3, 1.3, 16.0) with mν = m ν /m N . The barrier potential is z 0 = 0 in Fig.…”

Section: Tunnelling Spectroscopy Along C Axismentioning

confidence: 99%

Identifying possible pairing states in Sr2RuO4 by tunneling spectroscopy

2020

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We examine the tunneling spectroscopy of three-dimensional normal-metal/Sr2RuO4 junctions as an experimental means to identify pairing symmetry in Sr2RuO4. In particular, we consider three different possible pairing states in Sr2RuO4: spin-singlet chiral d-wave, spin-triplet helical p-wave, and spin-nematic f -wave ones, all of which are consistent with recent nuclear-magnetic-resonance experiments [A. Pustogow et al., Nature 574, 72 (2019)]. The Blonder-Tinkham-Klapwijk theory is employed to calculate the tunneling conductance, and the cylindrical two-dimensional Fermi surface of Sr2RuO4 is properly taken into account as an anisotropic effective mass and a cutoff in the momentum integration. It is pointed out that the chiral d-wave pairing state is inconsistent with previous tunneling conductance experiments along the c-axis. We also find that the remaining candidates, the spin-triplet helical p-wave pairing state and the spin-nematic f -wave ones, can be distinguished from each other by the in-plane tunneling spectroscopy along the a-and b-axes.

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“…Recent experimental works predict that the formation of Andreev Bound State (ABS) [95] and the flow of supercurrents [96] in SVs can be tuned and control via orientation of magnetization. Furthermore, it was also reported that at the ballistic junction of N|F|Triplet SC in Sr 2 RuO 4 [80], the orientation of magnetization can even control the pairing potential.…”

Section: Introductionmentioning

confidence: 97%

“…To understand feasibility of ferromangetism and superconductivity, and also the role of magnetization in F|S hybrids, many superconducting spintronic SVs had been extensively studied theoretically [76][77][78][79][80][81][82][83][84][85][86] and experimentally [87][88][89][90][91][92][93][94][95][96]. Previous works on F|S heterostructure and superconducting SVs strongly indicates that the superconducting critical temperature is dependent on the orientation of magnetization.…”

Section: Introductionmentioning

confidence: 99%

Spin transport and Spin Tunnelling Magneto-Resistance (STMR) of F|NCSC|F spin valve

Acharjee¹,

Goswami²

2020

Journal of Magnetism and Magnetic Materials

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In this work, we study the spin transport at the Ferromagnet|Noncentrosymmetric Superconductor (F|NCSC) junction of a Ferromagnet|Noncentrosymmetric Superconductor|Ferromagnet (F|NCSC|F) spin valve. We investigate the Tunnelling Spin-Conductance (TSC), spin current and Spin Tunnelling Magneto-Resistance (STMR), and their dependence on various important parameters like Rashba Spin-Orbit Coupling (RSOC), strength and orientation of magnetization, an external in-plane magnetic field, barrier strength and a significant Fermi Wavevector Mismatch (FWM) at the ferromagnetic and superconducting regions. The study has been carried out for different singlet-triplet mixing of the NCSC gap parameter. We develop Bogoliubov-de Gennes (BdG) Hamiltonian and use the extended Blonder -Tinkham -Klapwijk (BTK) approach along with the scattering matrix formalism to calculate the scattering coefficients. Our results strongly suggest that the TSC is highly dependent on RSOC, magnetization strength and its orientation, and singlet-triplet mixing of the gap parameter. It is observed that NCSC with moderate RSOC shows maximum conductance for a partially opaque barrier in presence of low external magnetic field. For a strongly opaque barrier and a nearly transparent barrier a moderate value and a low value of field respectively are found to be suitable. Moreover, NCSC with large singlet component is appeared to be useful. In addition, for NCSC with large RSOC and low magnetization strength, a giant STMR (%) is observed. We have also seen that the spin current is strongly magnetization orientation dependent. With the increase in bias voltage spin current increases in transverse direction, but the component along the direction of flow is almost independent. PACS numbers: 67.30.hj, 74.90.+n

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Theory of tunneling spectroscopy of normal metal/ferromagnet/spin-triplet superconductor junctions

Cited by 9 publications

References 78 publications

Observation of superconducting gap spectra of long-range proximity effect in Au/SrTiO3/SrRuO3/Sr2RuO4 tunnel junctions

Observation of superconducting gap spectra of long-range proximity effect in Au/SrTiO3/SrRuO3/Sr2RuO4 tunnel junctions

Identifying possible pairing states in Sr2RuO4 by tunneling spectroscopy

Spin transport and Spin Tunnelling Magneto-Resistance (STMR) of F|NCSC|F spin valve

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