O B A V I J E S T
SEYED ASHKAN MOGHADAM ZIABARI
održat će znanstveni kolokvij (doktorski seminar) iz Fizike kondenzirane tvari pod naslovom
Investigating electrical and magnetic properties of dimanganese phosphide under extreme conditions
Dimanganese phosphide (Mn₂P) crystallizes in a non-centrosymmetric hexagonal structure (space group P6̅2m), featuring two distinct Mn sites: Mn1 in a tetrahedral coordination and Mn2 in a tetragonal pyramidal environment. It undergoes an antiferromagnetic transition at a Néel temperature (TN) of ~103 K [1]. An early neutron diffraction study proposed a collinear antiferromagnetic structure with magnetic moments aligned along the a-axis, where only two of the three Mn2 and Mn1 atoms carry significant and small magnetic moments respectively[1]. In contrast, subsequent studies suggested a triangular spin arrangement with equal Mn1 moments and a higher TN of ~140 K [2]. Despite decades of study, the magnetic structure of Mn₂P remains unresolved.
Interest in Mn₂P has recent been renewed following the discovery of pressure-induced superconductivity in MnP [3] and the broader relevance of trasition metal phosphides for magnetic and electronic applications. Recent measurements of electrical resistivity and magnetic susceptibility have revealed strong anisotropy with respect to crystallographic direction, as well as indications of a spin-reorientation transition below TN. However, inconsistencies in reported magnetic moments and resistivity values persist even in recent studies [4, 5], underscoring the need for systematic studies on high-quality single crystals to establish the intrinsic properties of Mn₂P.
As a part of this doctoral research, the growth conditions of Mn₂P were optimized, enabling the synthesis of high-quality single crystals via the Sn-flux method. The crystals were characterized using complementary experimental techqiques and confirmed to be single-phase Mn2P with TN ~105 K. Notably, these samples exhibit lower residual resistivity than previously reported [3,4], indicating improved crystal quality.
Using these single crystals, the electrical and magnetic properties were investigated under high pressure and high magnetic fields. The Néel temperature initially increases with pressure up to 6 GPa, followed by a decrease up to the maximum applied pressure of 16 GPa. Magnetization measurements provide evidence of a spin-reorientation transition within the ab-plane around 50 K. Additionally, both positive and negative magnetoresistance with complex temperature dependence were observed, particularly for magnetic fields applied within the ab-plane. To gain insight into the electronic structure, advanced synchrotron-based soft X-ray spectroscopies (x-ray absorption and photoemission spectroscopies) were performed, revealing the valence state of Mn and a significant contribution of Mn 3d states at the Fermi level. The detailed experimental results will be discussed in this PhD seminar.
Seminar će se održati u ponedjeljak, 27. travnja 2026 godine u 15:00 sati u predavaonici F-201 Fizičkog odsjeka Prirodoslovno-matematičkog fakulteta Sveučilišta u Zagrebu.
Pozivaju se studenti doktorskog studija Fizike, smjer Fizika kondenzirane tvari, da prisustvuju seminaru, ako nisu spriječeni.
Voditelj smjera:
Prof. dr. sc. Ana Akrap
Pristupačnost
