Magnetic phase transitions and giant magnetoresistance in La1−xSmxMn2Si2 (0≤x≤1)

Abstract

The magnetic properties of La1−xSmxMn2Si2 (0≤x≤1) quasi-ternary layered intermetallic compounds have been studied by magnetic measurements. Based on the results of magnetic measurements, the x–T magnetic phase diagram of the compounds was defined. The concentration-dependent change in the magnetic state of the Mn sublattice in the compounds correlates with an unusual dependence of the type of interlayer Mn–Mn magnetic ordering on the intralayer Mn–Mn distance in the RMn2X2-type compounds. The compounds La1−xSmxMn2Si2 with x=0.25, 0.27 exhibit SmMn2Ge2-like magnetic behavior and giant magnetoresistance (−ΔR/R≈27%) at the field-induced antiferro-ferromagnetic metamagnetic phase transitions. The field-induced metamagnetic transitions were described in a model taking into account a strong Mn anisotropy, exchange magnetostriction and a strong dependence of the interlayer Mn–Mn exchange interactions on the Mn–Mn intralayer distance in the compounds.