[Zurück]

P. Gegenwart, Y. Tokiwa, T. Westerkamp, F. Weickert, J. Custers, J. Ferstl, C. Krellner, C. Geibel, P. Kerschl, K.-H. Müller, F. Steglich:
"High-field phase diagram of the heavy-fermion metal YbRh₂Si₂";
New Journal of Physics, 8 (2006), 171; S. 1 - 12.

High-field phase diagram of the heavy-fermion metal YbRh₂Si₂

P Gegenwart et al 2006 New J. Phys. 8 171 doi:10.1088/1367-2630/8/9/171

P Gegenwart1,3, Y Tokiwa1, T Westerkamp1, F Weickert1, J Custers1, J Ferstl1, C Krellner1, C Geibel1, P Kerschl2, K-H Müller2 and F Steglich1
1 Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
2 Leibniz Institute for Solid State and Materials Research, IFW Dresden, D-01069 Dresden, Germany
3 Author to whom any correspondence should be addressed.
E-mail: gegenwart@cpfs.mpg.de

Part of Focus on Correlated Electrons, Magnetism and Superconductivity in High Magnetic Fields

Abstract. The tetragonal heavy-fermion (HF) metal YbRh2Si2 (Kondo temperature TKap 25 K) exhibits a magnetic field-induced quantum critical point related to the suppression of very weak antiferromagnetic (AF) ordering (TN = 70 mK) at a critical field of Bc = 0.06 T (B⊥ c). To understand the influence of magnetic fields on quantum criticality and the Kondo effect, we study the evolution of various thermodynamic and magnetic properties upon tuning the system by magnetic field. At B > Bc, the AF component of the quantum critical fluctuations becomes suppressed, and FM fluctuations dominate. Their polarization with magnetic field gives rise to a large increase of the magnetization. At B* = 10 T, the Zeeman energy becomes comparable to kB TK, and a steplike decrease of the quasi-particle mass deduced from the specific-heat coefficient indicates the suppression of HF behaviour. The magnetization M(B) shows a pronounced decrease in slope at B* without any signature of metamagnetism. The field dependence of the linear magnetostriction coefficient suggests an increase of the Yb-valency with field, reaching 3+ at high fields. A negative hydrostatic pressure dependence of B* is found, similar to that of the Kondo temperature. We also compare the magnetization behaviour in pulsed fields up to 50 T with that of the isoelectronic HF system YbIr2Si2, which, due to a larger unit-cell volume, has an enhanced TK of about 40 K.

Received 31 March 2006
Published 1 September 2006

http://aleph.ub.tuwien.ac.at/F?base=tuw01&func=find-c&ccl_term=AC06588111

http://www.iop.org/EJ/abstract/1367-2630/8/9/171