Three and Four-Body Intervortex Forces in the Ginzburg-Landau Models of Single- and Multicomponent Superconductivity

扭转双层铜氧化物中具有可观 $s$ 波混合的拓扑多组分超导性

Topological multicomponent superconductivity with sizable $s$-wave admixture in twisted bilayer cuprates

通过 Ginzburg-Landau 分析和自洽微观平均场计算，研究扭转双层铜氧化物中 $s+d_1 e^{iϕ_1}+d_2 e^{iϕ_2}$ 序参量导致的三组分拓扑超导态，并发现向列 Kerr 各向异性可作为区分 $s+id$ 和 $d_1+e^{iϕ}d_2$ 态的特征信号。

Fluctuation-induced first order phase transitions in type-1.5 superconductors in zero external field

In a single-component Ginzburg-Landau model which possesses thermodynamically stable vortex excitations, the zero-field superconducting phase transition is second order even when fluctuations are included. Beyond the mean-field approximation the transition is described in terms of proliferation of vortex loops. Here we determine the order of the superconducting transition in an effective 3D vortex-loop model for the recently proposed multiband type-1.5 superconductors. The vortex interaction is nonmonotonic, i.e., exponentially screened and attractive at large separations, and short-range repu…

Shear Modulus Anomaly of Unconventional Superconductor in a Symmetry Breaking Field

Using Ginzburg-Landau formalism, we theoretically study the isothermal shear modulus anomaly of an unconventional superconductor with a multicomponent order parameter, when the superconducting transition is split by a symmetry-breaking field. Experimental signatures are proposed for both chiral and nematic superconductors. Particularly striking is the vanishing of $C_{66}$ across the lower transition to a nematic superconducting state. Our findings can guide future experiments and shed new lights on materials such as Sr$_2$RuO$_4$ and $M_x$Bi$_2$Se$_3$.

Length scales, collective modes, and type-1.5 regimes in three-band superconductors

The recent discovery of iron pnictide superconductors has resulted in a rapidly growing interest in multiband models with more than two bands. In this work we specifically focus on the properties of three-band Ginzburg-Landau models which do not have direct counterparts in more studied two-band models. First we derive normal modes and characteristic length scales in the conventional U(1) three-band Ginzburg-Landau model as well as in its time reversal symmetry broken counterpart with $U(1)\times Z_2$ symmetry. We show that in the latter case, the normal modes are mixed phase/density collective…

三组分超导电性：二阶约瑟夫森耦合效应

Three-component superconductivity: the effect of second-order Josephson couplings

本文基于三组分Ginzburg-Landau模型，通过解析求解基态和构建相图，揭示了二阶约瑟夫森耦合导致的五种基态和独特的Higgs-Leggett模式，为理解多组分超导的丰富物理提供了理论框架。

Type-1.5 superconductivity in multiband systems: magnetic response, broken symmetries and microscopic theory. A brief overview

A conventional superconductor is described by a single complex order parameter field which has two fundamental length scales, the magnetic field penetration depth λand the coherence length ξ. Their ratio κdetermines the response of a superconductor to an external field, sorting them into two categories as follows; type-I when κ<1/\sqrt{2} and type-II when κ>1/\sqrt{2} . We overview here multicomponent systems which can possess three or more fundamental length scales and allow a separate "type-1.5" superconducting state when, e.g. in two-component case ξ_1<\sqrt{2}λ<ξ_2. In that state, as a con…