Magnetic-field-induced structural phase transition and giant magnetoresistance in La0.85Ce0.15Fe12B6

Abstract

Magnetoelastic coupling, structural, magnetic, electronic transport, and magnetotransport properties of La 0.85 Ce 0.15 Fe 12 B 6 have been studied by a combination of macroscopic [magnetization, electrical resistivity, and magnetoresistance (MR)] and microscopic temperature-and magnetic-field-dependent x-ray powder diffraction measurements. The itinerant-electron system La 0.85 Ce 0.15 Fe 12 B 6 exhibits an antiferromagnetic (AFM) ground state and multiple magnetic transitions, AFM-ferromagnetic (FM) and FM-paramagnetic (PM), triggered by changes in both temperature and magnetic fields. At low temperatures, the field-induced first-order AFM-FM metamagnetic phase transition is discontinuous, manifesting itself by extremely sharp steps in magnetization as well as in MR and is accompanied by large magnetic hysteresis. A remarkably large negative MR of −73% was discovered. In addition, the time evolution of the electrical resistivity displays a colossal spontaneous jump when both the applied magnetic field and temperature are constant. Diffraction data reveal a magnetic-field-induced structural phase transition associated with the AFM-FM and PM-FM transformations. The lattice distortion is driven by magnetoelastic coupling and converts the crystal structure from rhombohedral (R 3m) to monoclinic (C2/m). The AFM and PM states are related to the rhombohedral structure, whereas the FM order develops in the monoclinic symmetry. A huge volume magnetostriction of ∼0.9% accompanies this symmetry-lowering lattice distortion. Meanwhile, a highly anisotropic thermal expansion involving giant negative thermal expansion with an average volumetric thermal expansion coefficient α V = −195 × 10 −6 K −1 was observed. The consistency seen in these different experimental data constitutes direct evidence of the strong correlations between charge, magnetic, and crystallographic degrees of freedom in this material.

Large piezoelectric response in ferroelectric/multiferroelectric metal oxyhalide MOX2 (M = Ti, V and X = F, Cl and Br) monolayers

“…For example, d 11 (37.758 pm/V) of TiOBr 2 is an order of magnitude larger than that of α-quartz (d 11 = 2.3 pm/V) 52 or d 33 of w-GaN (3.1 pm/V) 53 ; and also about 7 times higher than d 33 of w-AlN (5.1 pm/V) 53 . Note that group-IV monochalcogenide monolayers 19 As VOCl 2 and VOBr 2 monolayers have AFM ground state, we also study how their piezo-response will change in response to AFM-to-FM phase transition, which can be experimentally possible under an external magnetic field 54 . Note that FM-to-AFM transition can be a challenge in experiments.…”

“…As VOCl 2 and VOBr 2 monolayers have an AFM ground state, we also study how their piezo-response will change in response to the AFM-to-FM phase transition, which can be experimentally possible under an external magnetic field. 54 Note that the FM-to-AFM transition can be a challenge in experiments. We find that the AFM1-to-FM transition somewhat increases the elastic constants – especially C 22 – thus slightly decreases d 11 .…”

Large Piezoelectric Response in Ferroelectric/Multiferroelectric Metal Oxyhalides MOX2 (M = Ti, V and X = F, Cl and Br) Monolayers

“…Note that group-IV monochalcogenide monolayers [14] have relatively smaller indicating their softness C 11 and C 22 than MOX 2 monolayers. As VOCl 2 and VOBr 2 monolayers have AFM ground state, we also study how their piezo-response will change in response to AFM-to-FM phase transition, which can be possible under an external magnetic eld [44]. Note that FM-to-AFM transition can be a challenge in experiments.…”

Second-order phase transition of silicon from a band insulator to metal induced by strong magnetic fields

“…Furthermore, the giant magnetoresistance effect [13,14] and the colossal magnetoresistance effect [15][16][17][18] are known as magnetic field-induced phenomena, and they have led to a field of spintronics [19]. The magnetic field-induced phase transition has been attracting much attention so far and have been actively studied in recent years [20][21][22][23][24][25][26][27]. Thus, various physical properties are observed in materials immersed in a magnetic field, which are different from those of materials in the zero magnetic field.…”