Specific heat and magnetic susceptibility of single-crystalline ZnCrAlSe (x=0.15, 0.23)

E. Malicka (1) , T. Groń (2) , A. Ślebarski (2) , A.W. Pacyna (3) , J. Goraus (2) , M. Fijałkowski (2) , J. Heimann (2)

1 Institute of Chemistry
2 Institute of Physics
3 PAN - Polska Akademia Nauk = Polish Academy of Sciences = Académie polonaise des sciences

A correlation between the second critical field of the helix to paramagnetic transition and the magnetic specific heat -peak was found in ZnCrAlSe spinel single crystals with =0.15, 0.23. The specific heat peak is anomalously sharp for all finite magnetic fields used here and this points to a first order magneto-structural transition (from cubic to tetragonal symmetry). The (T)-peak is increasingly suppressed as the external field increases. Approaching the Neel temperature , a broad ac-magnetic susceptibility peak is observed for zero dc-magnetic field. That peak does not show an energy loss and thus points towards a return to a second order type of transition. The magnetic contribution to the specific heat displays a sharp peak at and is maximal at the spin fluctuation temperature =34K. is related to the maximum of the magnetic susceptibility at =40K (at 50kOe) in the spin fluctuation region, as evidenced by the entropy exceeding 90% of the entropy calculated classically for the complete alignment of the Cr spins, (2-x)Rln(2S+1). The X-ray photoelectron spectroscopy (XPS) data indicate that Al-substitution does not affect Cr 3 electronic configuration.

Mots clés: A. chalcogenides; B. crystal growth; C. photoelectron spectroscopy; D. magnetic properties; D. specific heat

Domaines: Science des matériaux [cond-mat.mtrl-sci]

E. Malicka, T. Groń, A. Ślebarski, A.W. Pacyna, J. Goraus, et al.. Specific heat and magnetic susceptibility of single-crystalline ZnCrAlSe (x=0.15, 0.23). Journal of Physics and Chemistry of Solids, 2011, 72 (8), pp.974. ⟨10.1016/j.jpcs.2011.05.008⟩. ⟨hal-00768586⟩