Chirality-selected crystal growth and spin polarization over centimeters of transition metal disilicide crystals

TL;DR

This study demonstrates controlled growth of chiral transition metal disilicide crystals and correlates their chirality with spin polarization effects, enabling non-destructive chirality detection over centimeter scales.

Contribution

It introduces a method for chirality-controlled crystal growth and links crystal chirality with spin polarization, advancing chiral material characterization.

Findings

Chiral crystals of NbSi$_{2}$ and TaSi$_{2}$ were successfully grown.

CISS-induced spin polarization was observed over centimeters.

CISS signals depend on the crystal's chirality.

Abstract

We performed a chirality-controlled crystal growth of transition metal disilicide NbSi$_{2}$ and TaSi$_{2}$ by using a laser-diode-heated floating zone (LDFZ) method. The crystal chirality was evaluated in the crystals of centimeters in length by performing single crystal X-ray diffraction as well as probing a spin polarization originating from chirality-induced spin selectivity (CISS) effect. The crystals of right-handed NbSi$_{2}$ and of left-handed TaSi$_{2}$ were obtained in the conventional LDFZ crystal growth, while the left-handed NbSi$_{2}$ and right-handed TaSi$_{2}$ crystals were grown by the LDFZ method with the composition-gradient feed rods. The spin polarization via the CISS was observed over centimeters in the NbSi$_{2}$ single crystals and the sign of the CISS signals was dependent on the chirality of crystals. The correlation between the crystal chirality and CISS signals indicates that the CISS measurements work as a non-destructive method for chirality determination even in centimeter-long specimens.