Electronically Controlled Magnetization Of Single-phase Multiferroic RCrO₃ Bulks And Films

Single-phase multiferroic materials have attracted much attention due to their magnetic order and ferroelectric order coupling.This paper studied and analyzed the ferroelectric polarization and electronically controlled magnetic mechanism of single-phase multiferroic materials TmCrO₃ and NdCrO₃.The main research contents and results are as follows:1、（1）TmCrO₃ bulks were prepared by the traditional solid state method.X-ray diffraction and scanning electron microscopy showed the samples were single phases with uniform grain size.The resistance-temperature curve（R-T）shows that the sample does not undergo a magnetic structure transition in the test temperature range.The magnetic and electronically controlled magnetic properties were measured;The electronically controlled magnetic results show that the electric field can effectively regulate the magnetic properties of the sample:in the T<T_comp temperature range,the electric field has a more significant influence on the magnetic moment of Tm³⁺,and in the T_comp<T<T_N temperature range,the electric field has a greater impact on the magnetic moment of Cr³⁺.（2）The（100）and（110）oriented TmCrO₃ films were prepared by pulsed laser deposition.The hysteresis loop results show that the samples have particular ferroelectric behaviour,which can be attributed to the lattice distortion of the samples;The electronically controlled magnetic influences of the thin film samples show that the effective regulation rate of magnetization can reach about 10%under the applied±400 k V/cm electric field intensity.This regulation behaviour is attributed to the non-collinear magnetic structure of the sample within the measured temperature range.2、（1）Single-phase NdCrO₃ bulk samples were synthesized by the solid-state method.The temperature dependence of magnetization shows that the spin reorientation(T_SR)leads to the magnetic structure transition at 37 K:When T<T_SR,the sample hasΓ₁ magnetic structure.When T_SR<T<T_N,the sample hasΓ₂ magnetic structure.The R-T curve clearly shows that there is an obvious magnetic structure phase transition at 37 K,which is consistent with the M-T curve.The electronically controlled magnetic results at 10 K and88 K show that the magnetic properties of the samples are effectively regulated after applying voltage due to the inverse DM interaction.（2）The（100）and（110）oriented NdCrO₃ thin films were prepared at the deposition temperature of 700°C,laser energy of300 m J and laser frequency of 3 Hz.The hysteresis loop results show that a low symmetry space group makes the NdCrO₃ thin film samples measure a certain degree of ferroelectric behaviour.The results of electronically controlled magnetism show that the sample’s effective electric field regulation rate at 10 K is about 14%,and the effective electric field regulation rate at 88 K can reach 32%.The difference between the two regulation rates is attributed to the existence of polar space group Pna2₁ at 88 K.