Nonmonotonic field dependence of the Néel temperature in the quasi-two-dimensional magnet [ Cu ( HF 2 ) ( pyz )

P. Sengupta,1,2 C. D. Batista,1 R. D. McDonald,2 S. Cox,2 J. Singleton,2 L. Huang,3 T. P. Papageorgiou,3 O. Ignatchik,3 T. Herrmannsdörfer,3 J. L. Manson,4 J. A. Schlueter,5 K. A. Funk,5 and J. Wosnitza3 1Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA 2MPA-NHMFL, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA 3Hochfeld-Magnetlabor Dresden (HLD), Forschungszentrum Dresden-Rossendorf, P.O. Box 510119, D-01314 Dresden, Germany 4Department of Chemistry and Biochemistry, Eastern Washington University, Cheney, Washington 99004, USA 5Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA Received 26 September 2008; published 23 February 2009