Quantum Bicriticality in the Heavy-Fermion Metamagnet YbAgGe

TitleQuantum Bicriticality in the Heavy-Fermion Metamagnet YbAgGe
Publication TypeJournal Article
Year of Publication2013
AuthorsTokiwa Y, Garst M, Gegenwart P, Bud'ko SL, Canfield PC
Journal TitlePhysical Review Letters
Volume111
Pages116401
Date Published09
Type of ArticleArticle
ISBN Number0031-9007
Accession NumberWOS:000324229900012
Keywordscriticality, TRANSITIONS
Abstract

Bicritical points, at which two distinct symmetry-broken phases become simultaneously unstable, are typical for spin-flop metamagnetism. Interestingly, the heavy-fermion compound YbAgGe also possesses such a bicritical point (BCP) with a low temperature T-BCP approximate to 0.3 K at a magnetic field of mu H-0(BCP) approximate to 4.5 T. In its vicinity, YbAgGe exhibits anomalous behavior that we attribute to the influence of a quantum bicritical point that is close in parameter space yet can be reached by tuning T-BCP further to zero. Using high-resolution measurements of the magnetocaloric effect, we demonstrate that the magnetic Gruneisen parameter Gamma(H) indeed both changes sign and diverges as required for quantum criticality. Moreover, Gamma(H) displays a characteristic scaling behavior but only on the low-field side H <= H-BCP, indicating a pronounced asymmetry with respect to the critical field. We speculate that the small value of T-BCP is related to the geometric frustration of the Kondo lattice of YbAgGe.

URL<Go to ISI>://WOS:000324229900012
DOI10.1103/PhysRevLett.111.116401