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Jaechul Lee

Publications and source records attributed to Jaechul Lee.

5 recordsLinked to original sources

A Dirichlet form approach to the potential theory of $m$-subharmonic functions

On a bounded open subset of $\mathbb{C}^n$, we study the Dirichlet form induced by an admissible pair $(θ,μ)$, where $μ$ is a positive Radon measure and $$θ=dd^c u_1\wedge\cdots\wedge dd^c u_{m-1}\wedge(dd^c \lvert z\rvert^2)^{n-m}$$ for locally bounded $m$-subharmonic functions $u_1,\dots,u_{m-1}$. We prove that locally bounded $m$-subharmonic functions belong locally to the domains of these Dirichlet forms and are quasi-continuous with respect to the induced capacities. We establish a monotonicity property for Dirichlet forms, which motivates the introduction of $μ$-quasi-monotone convergence of $m$-subharmonic functions. The natural embeddings into these domains are continuous with respect to this convergence. These results yield new proofs of the commutativity and continuity of complex Hessian operators. Using this framework, we characterize quasi-continuity with respect to the induced capacity for an arbitrary $m$-subharmonic function in terms of its pole set having zero measure $μ$, or equivalently, zero induced capacity. On bounded strictly $m$-pseudoconvex domains, we prove that the Bedford--Taylor capacity for $m$-subharmonic functions and the capacities induced by the corresponding Dirichlet forms have the same null sets. We further characterize $m$-polar sets in terms of Dirichlet forms and stochastic processes, extending the corresponding characterization of pluripolar sets due to Fukushima and Okada to the $m$-subharmonic setting.

math.CV↗

Anomalous proximity effect of a spin-singlet superconductor with a spin-orbit interaction

The anomalous proximity effect of a spin-triplet $p$-wave superconductor has been known as a part of the Majorana physics and is explained by the penetration of zero-energy states from a surface of a superconductor to a dirty normal metal. We demonstrate that a spin-singlet $d$-wave superconductor without any surface zero-energy states exhibits the anomalous proximity effect in the presence of a specific spin-orbit interaction. The results show the quantization of the zero-bias conductance in a dirty normal-metal/superconductor junction. We also discuss a relation between our findings and results in an experiment on a CoSi$_2$/TiSi$_2$ junction.

cond-mat.supr-con↗

Strong anomalous proximity effect from spin-singlet superconductors

The proximity effect from a spin-triplet $p_x$-wave superconductor to a dirty normal-metal has been shown to result in various unusual electromagnetic properties, reflecting a cooperative relation between topologically protected zero-energy quasiparticles and odd-frequency Cooper pairs. However, because of a lack of candidate materials for spin-triplet $p_x$-wave superconductors, observing this effect has been difficult. In this paper, we demonstrate that the anomalous proximity effect, which is essentially equivalent to that of a spin-triplet $p_x$-wave superconductor, can occur in a semiconductor/high-$T_c$ cuprate superconductor hybrid device in which two potentials coexist: a spin-singlet $d$-wave pair potential and a spin--orbit coupling potential sustaining the persistent spin-helix state. As a result, we propose an alternative and promising route to observe the anomalous proximity effect related to the profound nature of topologically protected quasiparticles and odd-frequency Cooper pairs.

cond-mat.supr-con↗

Odd-parity pairing correlations in a d-wave superconductor

We theoretically study the effects of spin-orbit interactions on symmetry of a Cooper pair in a spin-singlet d-wave superconductor in two-dimension. The pairing symmetry is analyzed in terms of the anomalous Green's function which is obtained by solving the Gor'kov equation analytically. A spin-orbit interaction induces a spin-triplet p-wave pairing correlation in a uniform superconductor. An odd-frequency spin-triplet s-wave pairing correlation appears at a surface of such superconductor as a result of breaking inversion symmetry locally. We also discuss a close relationship among the odd-frequency pairing correlation, chirality of surface bound states at the zero energy, and the anomalous proximity effect. The obtained results enable us to design a superconductor which causes the strong anomalous proximity effect.

cond-mat.supr-con↗

Proximity effect in a ferromagnetic semiconductor with spin-orbit interactions

We study theoretically the proximity effect in a ferromagnetic semiconductor with Rashba spin-orbit interaction. The exchange potential generates opposite-spin-triplet Cooper pairs which are transformed into equal-spin-triplet pairs by the spin-orbit interaction. In the limit of strong spin-orbit interaction, symmetry of the dominant Cooper pair depends on the degree of disorder in a ferromagnet. In the clean limit, spin-singlet $s$-wave Cooper pairs are the most dominant because the spin-momentum locking stabilizes a Cooper pair consisting of a time-reversal partner. In the dirty limit, on the other hand, equal-spin-triplet $s$-wave pairs are dominant because random impurity potentials release the locking. We also discuss the effects of the spin-orbit interaction on the Josephson current.

cond-mat.supr-con↗