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Regensburg 2010 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 27: CE: Poster Session

TT 27.15: Poster

Wednesday, March 24, 2010, 14:00–18:00, Poster D1

Low-temperature magnetization measurements on Yb(Rh0.93Co0.07)2Si2 — •Luis Pedrero, Manuel Brando, Cornelius Krellner, Christoph Geibel, and Frank Steglich — Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, 01187 Dresden, Germany

In the heavy-fermion compound Yb(Rh0.93Co0.07)2Si2 a detailed study of the thermodynamic and transport properties at low temperature has shown that the energy scale T*(H), associated with the Fermi surface reconstruction, vanishes inside the magnetic phase TN(H), where TN=0.4 K at zero field [1]. This discovery raises questions as (i) which energy scale is more relevant for quantum criticality in this system, (ii) where are located the strongest signatures of quantum fluctuations (at the critical field of T* or of TN) and (iii) which is their intrinsic nature.
To get more insights, we have performed several isofield M(T) and isothermal M(H) magnetization measurements on a high-quality single crystal of Yb(Rh0.93Co0.07)2Si2, to obtain a magnetization grid M(T,H) across the magnetic phase diagram. According to the definition of the Grüneisen ratio ΓH = −(dM/dT)H/CH and the Maxwell relation (dM/dT)H=(dS/dH)T we could then map the entropy S(H) in and outside the magnetic phase and - supported by specific heat measurements - analyse the divergence of ΓH(T) at both critical fields for T* and TN. A direct comparison with the theory will be presented.
[1] S. Friedemann et al., Nat. Phys. 5 (2009) 465.

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