Abstract
Magnetic properties of the LaMn2Si2 and La0.6R0.4Mn2Si2 (R = Sm, Tb, Gd) compounds with layered ThCr2Si2-type structure have been studied using quasi-single-crystalline and polycrystalline samples. Substitution of the R atoms for La decreases the interatomic distances and changes the ordering of the Mn sublattice from ferromagnetic to antiferromagnetic. Magnetic structure of the substituted compounds has been found to depend on the anisotropy of R ions. The Sm moments are oriented in the basal plane and weakly coupled with the Mn sublattice. For R = Tb, frustrations prevent the formation of long-range magnetic ordering in Tb sublattice. For the system with Gd, the antiferromagnetic Mn-Mn and Gd-Mn interactions lead to a change of magnetic anisotropy from the easy-axis to the easy-plane type.
Highlights
Intermetallic compounds RMn2X2 (R is a rare earth element, X is Si or Ge) crystallize in a body-centered tetragonal ThCr2Si2-type structure
In order to reveal the contribution of rare-earth sublattice to the magnetic state and magnetic phase transitions in RMn2Si2 with antiferromagnetic interlayer Mn-Mn coupling, we studied magnetic properties of several La1-xRxMn2Si2 (R = Sm, Tb and Gd) compounds for which the in-plane Mn-Mn distance is below its critical value dc
In order to determine contribution of magnetic rare-earth sublattice to the formation of magnetic structures and magnetic phase transitions in RMn2Si2 compounds with layered ThCr2Si2-type structure, we studied magnetic properties of the LaMn2Si2 and La0.6R0.4Mn2Si2 (R = Sm, Tb, Gd) using quasi-single-crystalline and aligned polycrystalline samples
Summary
Intermetallic compounds RMn2X2 (R is a rare earth element, X is Si or Ge) crystallize in a body-centered tetragonal ThCr2Si2-type structure (space group I4/mmm). Numerous systematic studies of different ternary and quasi-ternary RMn2X2 compounds have shown that the exchange interactions between adjacent Mn layers st√rongly depend on the in-plane Mn– Mn distance, dMn-Mn, and on the lattice constant a = 2dMn - Mn.[1,2,7] For the compounds in which dMn-Mn > dc ≈ 0.285 – 0.287 nm, the intralayer in-plane alignment is antiferromagnetic and the interlayer coupling is ferromagnetic. In order to reveal the contribution of rare-earth sublattice to the magnetic state and magnetic phase transitions in RMn2Si2 with antiferromagnetic interlayer Mn-Mn coupling, we studied magnetic properties of several La1-xRxMn2Si2 (R = Sm, Tb and Gd) compounds for which the in-plane Mn-Mn distance is below its critical value dc. The electron f shell of the Sm and Tb ions is characterized by the Stevens factor of opposite signs, which can provide various orientations of magnetic moments of the R ions
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