Manipulation of Jeff=3/2 states by tuning the tetragonal distortion

TL;DR

This paper demonstrates how tuning tetragonal distortion via epitaxial strain can manipulate Jeff=3/2 and S=1/2 quantum states in 4d/5d compounds, enabling quantum phase transitions and magnetic property control.

Contribution

It reveals the role of tetragonal distortion in controlling Jeff states and proposes a method to engineer quantum states in 4d/5d materials.

Findings

Tetragonal distortion determines ground states as Jeff=3/2 or S=1/2.

Epitaxial strain can modulate orbital occupation and induce quantum phase transitions.

Significant changes in local magnetic moments are achieved through state manipulation.

Abstract

The spin-orbit entangled quantum states in 4d/5d compounds, e.g., the Jeff=1/2 and Jeff=3/2 states, have attracted great interests for their unique physical roles in unconventional superconductivity and topological states. Here, the key role of tetragonal distortion is clarified, which determines the ground states of 4d1/5d1 systems to be the Jeff=3/2 one (e.g. K2NbCl6) or S=1/2 one (e.g. Rb2NbCl6). By tuning the tetragonal distortion via epitaxial strain, the occupation weights of dxy/dyz/dxz orbitals can be subtly modulated, competing with the spin-orbit coupling. Consequently, quantum phase transitions between S=1/2 state and Jeff=3/2 state, as well as between different Jeff=3/2 states, can be achieved, resulting in significant changes of local magnetic moments. Our prediction points out a reliable route to engineer new functionality of Jeff states in these quantum materials.