Electronic structure, chemical bonding, and magnetic properties in the intermetallic seriesSc2Fe(Ru1−xRh

Abstract

First-principles, density-functional studies of the electronic structure, chemical bonding, ground-state magnetic ordering, and exchange-interaction parameters have been performed for the entire Sc 2 Fe͑Ru 1−x Rh x ͒ 5 B 2 series of magnetic compounds. The results indicate that their magnetic properties depend in an extremely sensitive way on the degree of band filling and bandwidth. Continuous substitution of Ru by Rh changes the ground state from an antiferromagnet to a ferromagnet, as well as increases the effective spin moment caused by filling the bands with five additional electrons per formula unit together with a narrowing of the 4d band. The correlations between the character of the chemical bonding and the resulting exchange couplings are discussed. The enhancement of Fe-Fe exchange coupling caused by Rh/ Ru atoms is estimated. Trends for the macroscopic ordering temperatures are correctly reproduced.

Rational Synthetic Tuning between Itinerant Antiferromagnetism and Ferromagnetism in the Complex Boride Series Sc2FeRu5−nRhnB2 (0≤n≤5)

“…This result was correctly reproduced by first principles density-functional calculations of the ground-state magnetic ordering and exchange-interaction parameters [16] and it nicely corroborates the qualitative ideas at the very beginning of this research. [6] Phases isoelectronic with Sc 2 FeRu 5Àn Rh n B 2 A C H T U N G T R E N N U N G (0 n 5)…”

“…First principles LMTO-ASA calculations, however, have already revealed antiferromagnetic Fe-Fe exchange interactions for the 61 VE phase with a complicated type of magnetic ordering, namely antiferromagnetism with incommensurate ordering vectors. [16] Sc 2 FeRu 2 Rh 3 B 2 A C H T U N G T R E N N U N G (63 VE) and Sc 2 FeRuRh 4 B 2 A C H T U N G T R E N N U N G (64 VE): Both phases are ferromagnets exhibiting spontaneous magnetization below T C = 300 and 350 K respectively (T C is deduced from the intersection of a linear fit of the steepest part of the magnetization curve with T at low applied fields [17] ), and m a is 3.0 m B and 3.1 m B , respectively, at 4 K and B 0 = 5 T (see Figures 3 and 4). The paramagnetic region of the phase with 63 VE obeys the Curie-Weiss law at T > 500 K (see Figure 5) with q % + 375 K and C = 2.78 10 À5 m 3 K mol netically at 2 T. According to their hysteresis loops remanence and coercive field are very small, so that both intermetallics can be classified as soft ferromagnets such as Sc 2 FeRh 5 B 2 (65 VE).…”

A Delicate Balance between Antiferromagnetism and Ferromagnetism: Theoretical and Experimental Studies of A2MRu5B2 (A=Zr, Hf; M=Fe, Mn) Metal Borides

“…[18] Te tragonal Ti 3 Co 5 B 2 (space group P4/mbm,n o. [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] The crystal structure of the ternary variants is formed by face-connected trigonal, tetragonal, andp entagonal prisms of T/T'-atoms (electron-rich transition metals such as Co, Rh, Ir,R u). [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] The crystal structure of the ternary variants is formed by face-connected trigonal, tetragonal, andp entagonal prisms of T/T'-atoms (electron-rich transition metals such as Co, Rh, Ir,R u).…”

“…Of much interest are the quaternary variants containing the magnetic elements M = Fe, Mn, and Co, which reside in tetragonal prisms (Figure 1b)a nd form chains of Ma toms along [0 01]. [19,26] Interestingly,t he transition from antiferromagnetism to ferromagnetism was realized by means of av alence electron (VE) dependence study in the series Sc 2 FeRu 5Àx Rh x B 2 (x = 0-5, VE = 60-65). For example, antiferromagnetism in Sc 2 FeRu 5 B 2 ,f erromagnetism in Sc 2 FeRh 5 B 2 ,o r metamagnetism in Sc 2 FeIr 5 B 2 , [24,25] all of which contain the same magnetic element iron.…”

Directin situmeasurement of coupled magnetostructural evolution in a ferromagnetic shape memory alloy and its theoretical modeling

“…[67,68] in the lowest approximation to the spin Green function, which in turn corresponds to the virtual crystal approximation (VCA) (for further details, please see Supplementary Material [39]; Ref. [69][70][71][72][73][74]). Since the Ni magnetic moments cannot be described as rigid and the Ni sublattice cannot support magnons [66], we only consider Mn-Mn interactions in the Heisenberg Hamiltonian.…”