TR 288 - Elasto-Q-Mat: Research Data

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From valence fluctuations to long-range magnetic order in EuPd2(Si1−xGex)2 single crystals, original data from the figuresPaper
2023-06-12
Krellner, Cornelius
EuPd2Si2 is a valence-fluctuating system undergoing a temperature-induced valence crossover at T_V=160 K. We present the successful single-crystal growth using the Czochralski method for the substitution series EuPd2(Si1−xGex)2, with substitution levels x < 0.15. A careful determination of the germanium content revealed that only half of the nominal concentration is built into the crystal structure. From thermodynamic measurements it is established that T_V is strongly suppressed for small substitution levels and antiferromagnetic order from stable divalent europium emerges for x ~ 0.10. The valence transition is accompanied by a pronounced change of the lattice parameter a of order 1.8%. In the antiferromagnetically ordered state below T_N = 47 K, we find sizable magnetic anisotropy with an easy plane perpendicular to the crystallographic c direction. An entropy analysis revealed that no valence fluctuations are present for the magnetically ordered materials. Combining the obtained thermodynamic and structural data, we construct a concentration-temperature phase diagram demonstrating a rather abrupt change from a valence-fluctuating to a magnetically ordered state in EuPd2(Si1−xGex)2.
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