AUTHORS: Rafał Michalski, Jakub Zygadło
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ABSTRACT: We present the results of non-free parameter calculations of properties of HoAl2 and ErAl2 single crystals, performed with our new computation system called ATOMIC MATTERS MFA [1, 2]. A localized electron approach was applied to describe the electronic structure evolution of Ho and Er ions over a wide temperature range and estimate Magnetocaloric Effect (MCE). Thermomagnetic properties of HoAl2 and ErAl2 were calculated based on the fine electronic structure of the 4f^10 and 4f^11 electronic configuration of the Ho and Er ions, respectively. Our calculations yielded: magnetic moment value and direction; single-crystalline magnetization curves in zero field and in external magnetic field applied in various directions m(T,Bext); the 4f-electronic components of specific heat c4f(T,Bext); and temperature dependence of the magnetic entropy and isothermal entropy change with external magnetic field -ΔS(T,Bext). The cubic universal CEF parameters values used for all CEF calculations was taken from [3] and recalculated for universal cubic parameters set for the RAl2 series: A4=+7.164Ka0 and A6 =-1.038Ka0. Magnetic properties were found to be anisotropic due to cubic Laves phase C15 crystal structure symmetry. These studies reveal the importance of multipolar charge interactions when describing thermomagnetic properties of real 4f electronic systems and the effectiveness of an applied self-consistent molecular field in calculations for magnetic phase transition simulation.
KEYWORDS: HoAl2, ErAl2, RAl2, Laves Phase, CEF, MFA, MCE, Atomic Matters
REFERENCES:
[1] Rafał Michalski, Jakub Zygadło. Describing the Fine Electronic Structure and Predicting Properties of Materials with ATOMIC MATTERS Computation System. Proceedings: 18th Int. Conf. on Physics, Mathematics and Computer Science - Dubai UE 01.06.2016. http://waset.org/publications/10004653/pdf.
[2] Rafał Michalski, Jakub Zygadło, Thermal dependences of single ionic, magnetic properties of materials in ordered state, calculated with ATOMIC MATTERS MFA computation system– Poceedengs: 7th IIF-IIR International Conference on Magnetic Refrigeration at Room Temperature, Thermag VII - Torino ITALY, 11-14 September 2016. – in printing
[3] H.G. Purwins and A. Leson, Adv. Phys. 39 (1990) 309.
[4] L.A. Gil, J.C.P. Campoy, E.J.R. Plaza and M.V. de Souza, Journal of Magnetism and Magnetic Materials 409 (2016) 45–49.
[5] Magnetic and magnetoresistive properties of cubic Laves phase HoAl2 single crystal, M. Patra, S. Majumdar and S. Giri, Y. Xiao, T. Chatterji (2011) arXiv:1107.1975
[condmat.mtrl-sci]
[6] F. W. Wang, X. X. Zhang, and F. X. Hu, Appl. Phys. Lett., Vol. 77, No. 9 (2000)1360.
[7] P.O.Ribeiro, B.P.Alho, T.S.T.Alvarenga, E.P.Nóbrega, V.S.R.deSousa, A.Magnus G.Carvalho, A.Caldas, N.A.deOliveira, P.J.vonRanke, Journal of Magn. Magn. Mater. 379 (2015) 112–116.
[8] P.Wikusa, E.Canavan, S.T.Heine, K.Matsumoto, T.Numazawa Cryogenics Preprint (2014)
[9] Software website: www.atomicmatters.eu
[10] C. Rudowicz, C. Y Chung, The generalization of the extended Stevens operators, J. Phys.: Condens. Matter 16 (2004) 5825–5847.
[11] P.G.de Gennes J.Phys.Radiat 23 (1962) 5010.
[12] M. T. Hutchings, Solid State Phys. 16 (New York (1964) 227.
[13] B. G. Wybourne, Symmetry Principles and Atomic Spectroscopy, J. Wiley and Sons, New York (1970).
[14] A. Abragam and B. Bleaney, EPR of Transition Ions, Clarendon Press, Oxford (1970).
