Events

Department of Magnetic Reseach Seminar

Zintl phases UCu2P2 and EuZn2P2

prof. Ladislav Havela

Uniwersytet Karola w Pradze w Czechach

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 ())

The seminar will be held remotely in the Microsoft Teams application. In order to participate in the event, you must join the Seminarium OBM team. You can join it permanently using the access code ol7omod (this applies to people with an account in the intibs.pl domain, other people please contact Prof. Adam Pikul , Prof. INTiBS PAN ())

Abstract:

Zintl-like phases can be seen as compounds of an electropositive cation which donates valence electrons to form a framework of covalently bonded poly-atomic anions with a closed valence shell. Because of the nature of the chemical bonding, Zintl phases are located at the borderline between valence compounds, which are typical insulators, and the intermetallic compounds, which are typical metals. The situation of a tunable narrow gap is interesting for practical reasons (thermoelectric properties).
A specific situation offering an excellent opportunity of well-defined anisotropy of magnetic and transport properties is offered by the trigonal structure of the CaAl2Si2 type (P-3m), formed by alternating cationic (Ca) and anionic (Al-Si) layers. The ionicity dwells in the donation of valence electrons of a cation to stabilize the anionic framework. Incorporating magnetic atoms in such a compound gives an intriguing opportunity to explore interplay of magnetic degrees of freedom and electronic structure, as e.g. a moment reorientation in magnetically ordered state, or disordering in the paramagnetic state, tuning the band gap width.
So far lot of research interest has been devoted to Eu2+ compounds and their U isotype, UCu2P2, both being a subject of the Prague-Wroclaw collaboration. What do the Eu and U compounds have in common? We tried to explore more details including high-pressure studies, as magnetic ordering temperatures increase in both cases as a function of hydrostatic pressure. The U and Eu compounds are in many respects rather different. EuZn2P2 is a narrow gap semiconductor, UCu2P2 is a half-semi-metal, but both exhibit an interesting interplay of magnetism and electronic structure.