arXiv subjects

Trent M. Kyrk

Publications and source records attributed to Trent M. Kyrk.

3 recordsLinked to original sources

arXiv2026

Quantum-Material Josephson Junctions: Unconventional Barriers, Emerging Functionality

Josephson junctions translate quantum phase coherence into an electrical response and underpin superconducting sensors and quantum circuits. In conventional junctions, the barrier acts primarily as a passive weak link, however, when the barrier is a quantum material with its own internal degrees of freedom like magnetism, strong correlations, or switchable polarization, the Josephson effect becomes a sensitive probe of symmetry and many-body physics in the interlayer. Here we review progress in quantum-material Josephson junctions, (QMJJ) focusing on three rapidly advancing barrier families: 1. magnetic barriers, where exchange, noncollinearity, and spin-active scattering enable 0-π-ϕ ground states, singlet-triplet conversion, and nonreciprocal transport, 2. correlated barriers, where proximity effects acquire many-body character and recent van der Waals Kagome Mott interlayers exhibit field-free Josephson diode behavior, and 3. ferroelectric and multiferroic barriers, where nonvolatile polarization provides an internal control knob and can produce superconducting memory and memristive dynamics.

cond-mat.supr-con↗

arXiv2025

Driving the field-free Josephson diode effect using Kagome Mott insulator barriers

Josephson junctions (JJs), devices consisting of two superconductors separated by a barrier, are of great technological importance, being a cornerstone of quantum information processing. Classical understanding of superconductor-insulator-superconductor JJs is that conventional insulator's properties, other than magnetism, do not significantly influence the junction's behavior. However, recent work on quantum material (QM) JJs - using Mott insulator Nb3Br8 - resulted in magnetic field-free non-reciprocal superconductivity, termed the Josephson diode effect (JDE), implying the QM's intrinsic properties can modulate superconductivity in non-trivial ways. To date, the underlying mechanism and dependence of the JDE on correlation strength (U/t) has not been elucidated. Here we fabricate QMJJs using correlated Kagome insulators with varying U/t, Nb3X8 (X=Cl, Br, I), observing a decreasing trend of the field-free JDE with Nb3Cl8 reaching ~48% efficiency, Nb3Br8 ~6%, and Nb3I8 having no discernible JDE, matching the trend of decreasing U/t from Cl to I and suggesting correlation in insulators drives the field-free JDE.

cond-mat.supr-con↗

arXiv2025

Anomalous refractive index modulation and giant birefringence in 2D ferrielectric CuInP$_2$S$_6$

2D ferroelectric (FE) materials have opened new opportunities in non-volatile memories, computation and non-linear optics due to their robust polarization in the ultra-thin limit and inherent flexibility in device integration. Recently, interest has grown in the use of 2D FEs in electro-optics, demanding the exploration of their electronic and optical properties. In this work, we report the discovery of an unprecedented anomalous thickness-dependent change in refractive index, as large as $δn$ $\sim$ 23.2$\%$, in the 2D ferrielectric CuInP$_2$S$_6$, far above the ultra-thin limit, and at room temperature. Furthermore, CuInP$_2$S$_6$ exhibits a giant birefringence in the blue-ultraviolet regime, with a maximum $\vert n_{OOP} - n_{IP}\vert$ $\sim$ 1.24 at $t \sim$ 22 nm and $λ$ = 339.5 nm, which is, to the best of our knowledge, the largest of any known material in this wavelength regime. We relate changes in CuInP$_2$S$_6$ optical constants to changes in the Cu(I) FE polarization contribution, influenced by its ionic mobility, opening the door to electronic control of its optical response for use in photonics and electro-optics.

cond-mat.mtrl-sci↗