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Seminarium Oddziału Badań Magnetyków

14:00 Wednesday, 19-10-22
Microsoft Teams

The study of electronic structure and magnetic properties of two series of light actinide U2TGa3 and Np2TGa3 (T = Pd, Pt) intermetallics from the first-principles

dr Mane Sahakyan

Oddział Badań Magnetyków INTiBS PAN we Wrocławiu

Seminarium odbędzie się zdalnie w aplikacji Microsoft Teams. W celu wzięcia udziału w wydarzeniu należy dołączyć do zespołu Seminarium OBM.Można do niego dołączyć na stałe przy użyciu kodu dostępu ol7omod (dotyczy to osób posiadających konto w domenie intibs.pl, pozostałe osoby proszę o kontakt z prof. dr. hab.Adamem Pikulem, prof. INTiBS PAN ())


Due to the localized or itinerant nature of the 5f electrons, actinide compounds displaying various intriguing phenomena, such as the Kondo effect, heavy fermion behavior and etc., have been continuously studied in recent decades. Moreover, it can be noticed that in uranium intermetallic compounds the magnetic properties strongly correlate with the features of both the electronic and the crystal structure, since any small change can lead to large changes in magnetism.
In this report we present the theoretical investigation of the electronic structure and magnetic properties study of two series of light actinide compounds U2TGa3 and Np2TGa3 (T = Pd, Pt) crystallizing in an orthorhombic CeCu2-type structure (space group Imma). Based on the electrical resistivity, magnetization, magnetic susceptibility data, U-based compounds ordering antiferromagnetically [1, 2], while Np-based: ferromagnetically [3,4]. The magnitudes of ordered uranium magnetic moments obtained by neutron-diffraction patterns are evaluated to 0.32(5) μB/U and 0.38(5) μB/U for U2PdGa3 and U2PtGa3, respectively, which are strongly reduced in comparison of moments of free uranium ions (U3+ (3.6 μB/U) and U4+ (3.58 μB/U)). This fact and the number of other features prove the assumption that Kondo effect is operative in an antiferromagnetically ordered state. Employing Density functional theory methods we observe significant changes in the magnetic moments and electronic properties of these compounds. Using Full-Potential Linearized Augmented Plane-Wave (FP-LAPW) method [5], the electronic structure properties are discussed in terms of effects brought by the Coulomb interaction (U) and the Hund coupling (J). Moreover, taking into account the importance of orbital magnetism in uranium compounds the Orbital Polarization Correction (OPC) was used to model the magnetic properties in the Full-potential local-orbital (FPLO) method [6].
The electronic structure of ferromagnetic Np2PdGa3 and Np2PtGa3 intermetallics is also investigated by means of the DFT theory. Including the relativistic effects of spin-orbit coupling, and Hubbard term corrections, meaningful changes in the magnetic and electronic properties of Np2(Pd,Pt)Ga3 are discussed. In particular, the reduction in magnetic moments and DOS enhancement at the Fermi energy are in good agreement with the Kondo lattice characteristics.
[1] Tran V. H., J. Phys.: Condens. Matter 8, 6267 (1996).
[2] Tran V. H., Steglich F., and Andre G., Phys. Rev. B 65, 134401 (2002).
[3] V. H. Tran, J.-C. Griveau, R. Eloirdi, W. Miiller, and E. Colineau, Phys. Rev. B 82, 094407 (2010)
[4] V. H. Tran, J.-C. Griveau, R. Eloirdi, and E. Colineau, Phys. Rev. B 89, 054424 (2014)
[5] Wimmer, E.; Krakauer, H.; Weinert, M.; Freeman, A. J 1103/Phys RevB..1981, 24, 864 –875.
[6] K. Koepernik and H Eschrig, Phys. Rev. B 59, 1743 (1999). https://www.fplo.de/.

im. Włodzimierza Trzebiatowskiego
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