Superconductivity and Magnetism in Non-centrosymmetric System: Application to CePt<sub>3</sub>Si

Yanase, Youichi; Sigrist, Manfred

doi:10.1143/jpsj.77.124711

Cited by 97 publications

(128 citation statements)

References 87 publications

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“…18,19,20 In these superconductors, the admixture of even-and odd-parity pairings has been suggested theoretically. 21,22,23,24 Thus, we expect the mixing of parity also occurs in the present system. In this case, the change in the pairing symmetry under applied voltage is not a phase transition but a crossover between different parities.…”

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confidence: 50%

Electrically controlled superconducting states at the heterointerfaceSrTiO3/LaAlO3

et al. 2009

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We study the symmetry of Cooper pair in a two-dimensional Hubbard model with the Rashbatype spin-orbit interaction as a minimal model of electron gas generated at a heterointerface of SrTiO3/LaAlO3. Solving theÉliashberg equation based on the third-order perturbation theory, we find that the gap function consists of the mixing of the spin-singlet dxy-wave component and the spin-triplet (px ± ipy)-wave one due to the broken inversion symmetry originating from the Rashbatype spin-orbit interaction. The ratio of the d-wave and the p-wave component continuously changes with the carrier concentration. We propose that the pairing symmetry is controlled by tuning the gate voltage.PACS numbers: 74.25.Dw, 74.78.Fk, 71.10.Fd Recent development of technology of epitaxial growth makes it possible to fabricate heterointerface between two different transition-metal oxides. 1,2 The discovery of the generation of two-dimensional electron gas (2DEG) at the n-type heterointerface SrTiO 3 /LaAlO 3 attracts much interest 3 since both SrTiO 3 and LaAlO 3 are band insulators in the bulk material. It is also noted that this 2DEG shows superconductivity with transition temperature T c = 200 mK. 4 This superconductivity differs from the superconductivity of bulk SrTiO 3 with T c = 300 mK in the carrier concentration and the dimensionality of mobile electrons. 5 The discovery of superconductivity is significant since it is promising to control the superconducting states electrically by the applied voltage. Controlling the number of carrier by applied voltage in superconductors is one of the intriguing issues to understand the mechanism of the superconductivity. In cuprates, a superconducting region is located next to an antiferromagnetic phase in an n-T phase diagram. However, in cuprate superconductors, it is not easy to tune the number of carrier by external fields such as the magnetic field or the gate voltage since the number of carrier depends on material compositions. On the other hand, the carrier number of 2DEG at the heterointerface SrTiO 3 /LaAlO 3 can be tuned by the gate voltage since the carrier is generated by the polar and unpolar nature of LaAlO 3 and SrTiO 3 , respectively. 6 Actually, electrostatically tuned superconductor-metal-insulator transition was found to be accessible. 7,8,9 When the electron correlations (Coulomb interaction) are responsible to the superconductivity, the pairing symmetry depends on the number of carrier: The spin-triplet p-wave pairing is favored at low density, 10,11,12,13,14 while on the other hand, the spin-singlet d x 2 −y 2 -wave pairing is favored near half filling. 15,16 Thus, at the heterointerface of oxides with large Coulomb interaction, the phase transition between the spin-singlet and spin-triplet states can be observed by the applied voltage.Another characteristic feature at the heterointerface is lack of the inversion symmetry along the direction perpendicular to the interface (z-axis), which induces the asymmetric spin-orbit interaction called the Rashbatype spin-orbit intera...

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Electrically controlled superconducting states at the heterointerfaceSrTiO3/LaAlO3

et al. 2009

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“…We see the spin splitting caused by the Rashba spin-orbit coupling. The Rashba spin-orbit coupling is enhanced around the band crossing points, as shown in [16]. The Fermi surfaces for a carrier density n = 0.15 are shown in Fig.…”

Section: Numerical Resultsmentioning

confidence: 83%

“…Although our model does not explicitly take into account the Rashba spin-orbit coupling, the Rashba spin-orbit coupling derives from the combination of the odd parity hybridization term, H odd , and the LS coupling term, H LS [16]. We consider the s-wave superconductivity as expected in the bulk STO [17].…”

Section: Modelmentioning

confidence: 99%

Theory of Multi-Orbital Superconductivity in SrTiO₃/LaAlO₃Interface

Nakamura¹,

Yanase²

2014

Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2013)

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We investigate the superconductivity in two-dimensional electron systems formed in SrTiO 3 nanostructures. Our theoretical analysis is based on the three-orbital model, which takes into account t 2g orbitals of Ti ions. We find that the Rashba spin-orbit coupling stabilizes a quasi-one-dimensional superconducting phase at high magnetic fields along interfaces. This quasi-one-dimensional superconducting phase is protected against paramagnetic depairing effects by the Rashba spin-orbit coupling and realizes a large upper critical field H c2 beyond the Pauli-Clogston-Chandrasekhar limit.

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“…We assume b > 0 in this paper, while the cases of negative b have been discussed in Ref. 43. We focus on this situation in this paper.…”

Section: )mentioning

confidence: 99%

Ginzburg–Landau Analysis for the Antiferromagnetic Order in the Fulde–Ferrell–Larkin–Ovchinnikov Superconductor

Yanase

Sigrist

2011

J. Phys. Soc. Jpn.

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Antiferromangetic (AFM) order in the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superconducting state is analyzed on the basis of the Ginzburg-Landau theory. To examine the possible AFM-FFLO state in a heavy fermion superconductor CeCoIn5, we focus on the incommensurate AFM order characterized by the wave vector Q = Q0 ± qinc with Q0 = (π, π, π) and qinc[110] or [110] in the tetoragonal crystal structure. We formulate the two component Ginzburg-Landau model to discuss two denerate incommensurate AFM states with qinc [110] and [110]. Owing to the broken translation symmetry in the FFLO state, multiple phase diagram of single-q phase and double-q phase is obtained under the magnetic field along [100] or [010]. Magnetic properties in each phase are investigated and compared with the neutron scattering and nuclear magnetic resonance (NMR) measurements. An ultrasonic measurement is proposed for a future experimental study on the possible AFM-FFLO state in CeCoIn5. The field orientation dependence of the AFM order in CeCoIn5 is discussed.

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Superconductivity and Magnetism in Non-centrosymmetric System: Application to CePt₃Si

Cited by 97 publications

References 87 publications

Electrically controlled superconducting states at the heterointerfaceSrTiO3/LaAlO3

Electrically controlled superconducting states at the heterointerfaceSrTiO3/LaAlO3

Theory of Multi-Orbital Superconductivity in SrTiO₃/LaAlO₃Interface

Ginzburg–Landau Analysis for the Antiferromagnetic Order in the Fulde–Ferrell–Larkin–Ovchinnikov Superconductor

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Superconductivity and Magnetism in Non-centrosymmetric System: Application to CePt3Si

Cited by 97 publications

References 87 publications

Electrically controlled superconducting states at the heterointerfaceSrTiO3/LaAlO3

Electrically controlled superconducting states at the heterointerfaceSrTiO3/LaAlO3

Theory of Multi-Orbital Superconductivity in SrTiO3/LaAlO3Interface

Ginzburg–Landau Analysis for the Antiferromagnetic Order in the Fulde–Ferrell–Larkin–Ovchinnikov Superconductor

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Superconductivity and Magnetism in Non-centrosymmetric System: Application to CePt₃Si

Theory of Multi-Orbital Superconductivity in SrTiO₃/LaAlO₃Interface