100 MHz high-speed strain monitor using fiber Bragg grating and optical filter applied for magnetostriction measurements of cobaltite at magnetic fields beyond 100 T

TL;DR

This paper introduces a high-speed fiber Bragg grating-based strain monitor capable of measuring magnetostriction at magnetic fields exceeding 100 T, revealing field-induced lattice changes in LaCoO3.

Contribution

The development of a 100 MHz high-speed strain measurement system using FBG and optical filters for ultrahigh magnetic field applications is novel.

Findings

Measured magnetostriction of LaCoO3 up to 150 T.

Observed lattice elongations due to spin-state crossover.

Demonstrated capability for ultrahigh magnetic field measurements.

Abstract

High-speed 100 MHz strain monitor using fiber Bragg grating (FBG) and an optical filter has been devised for the magnetostriction measurements under ultrahigh magnetic fields. The longitudinal magnetostriction of LaCoO$_{3}$ has been measured at room temperature, 115, 7 and 4.2 K up to the maximum magnetic field of 150 T. The field-induced lattice elongations are observed, which are attributed to the spin-state crossover from the low-spin ground state to excited spin-states.