Magnetization and EPR studies of the single molecule magnet Ni$_4$ with integrated sensors

TL;DR

This paper presents the development of integrated sensors combining EPR and magnetization measurements to study the spin dynamics and energy relaxation in a Ni4 single molecule magnet at low temperatures.

Contribution

It introduces a novel integrated sensor platform combining a microstrip resonator and micro-Hall magnetometer for simultaneous EPR and magnetization studies.

Findings

Determined energy splitting between spin states of Ni4 magnet.

Observed changes in spin-population during microwave absorption.

Estimated energy relaxation times of the spin system.

Abstract

Integrated magnetic sensors that allow simultaneous EPR and magnetization measurements have been developed to study single molecule magnets. A high frequency microstrip resonator has been integrated with a micro-Hall effect magnetometer. EPR spectroscopy is used to determine the energy splitting between the low lying spin-states of a Ni$_4$ single crystal, with an S=4 ground state, as a function of applied fields, both longitudinal and transverse to the easy axis at 0.4 K. Concurrent magnetization measurements show changes in spin-population associated with microwave absorption. Such studies enable determination of the energy relaxation time of the spin system.