Electron spin resonance study of Na_{1-x}Li_xV_2O_5

TL;DR

This study uses electron spin resonance to investigate how lithium doping affects the magnetic phase transition and energy gap in sodium vanadate, revealing suppression of the dimerized phase with increased lithium content.

Contribution

It provides detailed ESR measurements showing how lithium doping suppresses the dimerized phase and alters the energy gap in NaV_2O_5, offering new insights into doping effects on quantum phase transitions.

Findings

Transition temperature Tsp decreases quadratically with lithium concentration.

Energy gap decreases linearly with lithium doping.

High-temperature susceptibility remains unaffected by doping.

Abstract

We measured X-band electron-spin resonance of single crystalline sodium vanadate doped with lithium, Na_{1-x}Li_xV_2O_5 for 0 < x < 1.3% . The phase transition into a dimerized phase that is observed at 34 K in the undoped compound, was found to be strongly suppressed upon doping with lithium. The spin susceptibility was analyzed to determine the transition temperature and the energy gap with respect to the lithium content. The transition temperature Tsp is suppressed following a square dependence of the lithium concentration while the energy gap is found to decrease linearly. At high temperatures (T>Tsp) the susceptibility remains nearly independent of doping.