From incommensurate correlations to mesoscopic spin resonance in YbRh2Si2

TL;DR

This study investigates spin fluctuations and incommensurate correlations near the quantum critical point in YbRh2Si2, revealing a field-induced mesoscopic spin resonance with localized spin precession.

Contribution

It provides new insights into the evolution of spin fluctuations and the discovery of a mesoscopic spin resonance in YbRh2Si2 near quantum criticality.

Findings

Ferromagnetic fluctuations evolve into incommensurate correlations at low temperatures.

A sharp intra doublet resonant excitation is induced by magnetic field.

The spin precession extends over a mesoscopic length scale of approximately 6 Å.

Abstract

Spin fluctuations are reported near the magnetic field driven quantum critical point in YbRh2Si2. On cooling, ferromagnetic fluctuations evolve into incommensurate correlations located at q0=+/- (delta,delta) with delta=0.14 +/- 0.04 r.l.u. At low temperatures, an in plane magnetic field induces a sharp intra doublet resonant excitation at an energy E0=g muB mu0 H with g=3.8 +/- 0.2. The intensity is localized at the zone center indicating precession of spin density extending xi=6 +/- 2 A beyond the 4f site.