STUDY OF MAGNETIZATION REVERSAL IN ORTHORHOMBIC PEROVSKITES WITH CATION Lu3+

F. E. LURGO; R. E. CARBONIO; O. BILLONI; C. MARTIN

Las Vegas

Conferencia; 2019 Annual Conference on Magnetism and Magnetic Materials; 2019

AIP Publishing, IEEE Magnetics Society

Rare earth orthoferrites and ortochromites of an ABO₃ composition, where A is a lanthanide and B is Fe or Cr, have been under study for several decades. This is because the materials with transition metal and rare earth ions show a variety of magnetic properties resulting from the coupling between the two magnetic sublattices. The strong interaction between these two sublattices of the total magnetic moment could produce the phenomena vastly studied:Magnetization Reversal (MR). The MR make this material suitable to spintronic, sensors andthermally assisted random access memory devices. The MR is phenomena in which the spontaneous magnetization changes its sign at a compensation temperature (Tcomp) under low magnetic field. These phenomena have been found in perovskites whose site B is occupied in simultaneous withtransition metal ions and the site S, with non-magnetic cation.Recent in our investigation group it was designed, synthetized and characterized the compound LuFe0.5Cr0.5O3 determining a Tcomp of 255K [1]. The MR of this compound it?s because the two metal transition cations showed antisymmetric exchange interactions or Dzyaloshinskii-Moriya interactions [2] leading to weak antiferromagnetic behavior (WF). Since the magnetic moment of Fe³⁺ are already ordered at room temperature, when the magnetic moment of Cr³⁺ are ordered a T~ 270 K, they do to the opposite direction to the moment of Fe³⁺, producing this effect the MR. Four members of the perovskite family LuFe1-xCrxO3 (x= 0; 0.25;0.5;0.75) have been synthesized with different thermal treatment and characterized. A systematic study of the crystal and magnetic structure was performed by neutron powder diffraction combined with magnetization measurements. All the compounds crystallize in a Pbnm orthorhombic. The study of the magnetic structure vs temperature showed the transition Γ2/Γ4 TM to Γ4 TM in the compound Cr-rich. The rest of the compositions showed Γ4 TM in all the temperatures in good agreement with the magnetic measurements [3]. The compounds with near to x=0.5 show MR (Figure 1) but if change the synthesis temperature, this phenomenon disappears. LuFe0.25Cr0.75O3 don?t show MR but with two different synthesis temperature the phenomenon appears. This results is because the different thermal treatment allows or not the cluster (inhomogeneous distribution of cations) formation. The magnetic behavior depends on the synthesis temperature and synthesis method of the compounds.We have performed MonteCarlo simulations using the following Hamiltonian of classical Heisenberg spins [4] lying in the nodes of a cubic lattice with N= (L x L x L) sites to reproduced the MR observed experimentally in a field cooling (FC) process (Figure 2) and the cluster formation according the different thermal treatment.