Spin Magnetic Structure Research Articles

Angle-resolved magnetoresistance in the strongly anisotropic quantum magnet TmB4

Precise angle-resolved magnetoresistance (ARMR) measurements in various magnetic fields enabled us to create illustrative distributions of $\mathrm{\ensuremath{\Delta}}\ensuremath{\rho}/\ensuremath{\rho}(\ensuremath{\varphi},\phantom{\rule{0.16em}{0ex}}H)$ in $\mathrm{Tm}{\mathrm{B}}_{4}$, where $\ensuremath{\varphi}$ is the angle between the sample $c$ axis and applied magnetic field $H$. These distributions reveal the charge transport anisotropy in this strongly Ising anisotropic quantum antiferromagnet with a geometrically frustrated Shastry-Sutherland lattice exhibiting fractional magnetization plateaus. While in the paramagnetic region $\mathrm{\ensuremath{\Delta}}\ensuremath{\rho}/\ensuremath{\rho}(\ensuremath{\varphi},\phantom{\rule{0.16em}{0ex}}H)$ reaches its maxima for $H\phantom{\rule{0.16em}{0ex}}\ensuremath{\perp}\phantom{\rule{0.16em}{0ex}}c$, below the N\'eel temperature ${T}_{N}=11.7$ K the situation is different. Here the main MR features appear for $H\ensuremath{\parallel}c$, i.e., along the easy axis of magnetic anisotropy, and correspond to magnetic phases and phase transitions between them. It is interesting that all the above features (maxima) related with the scattering of conduction electrons on spin magnetic structure are related with fractional magnetization plateaus. With increasing $\ensuremath{\varphi}$ MR anomalies shift to higher fields. Above the field of magnetic saturation, moreover, significant MR maxima have been observed at certain angles which correspond to specific directions in the crystal lattice, pointing to field directions in which the scattering of conduction electrons on the magnetic structure is the highest. Thus, ARMR appears to be a sensitive experimental tool reflecting the angular dependence of the interplay between charge carriers and magnetic structure as a function of temperature and applied magnetic field.

Study of structural, electrical and magnetic characterization of (1-x)BiFeO3-xBaTiO3 solid solution

The materials which exhibit coupled electric, magnetic, and structural order parameters, yield simultaneous effects of ferroelectricity, ferromagnetism, and ferroelasticity are referred as multiferroics. Multiferroic properties like ferromagnetism and ferroelectricity of BiFeO3 (BFO) have been reported to be enhanced by forming solid solution with BaTiO3 (BT) designated by BFO-BT. In the present investigations, a solid solution of (1-x)BFO-xBT (x = 0, 0.05, 0.10, 0.15, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.85, 0.90, and 1.0) single phase have been synthesized by solid state ceramic route. Structural, magnetic and electrical properties of single phase solid solution of BFO-BT have studied in detail to understand their multiferroic properties. In powder X-ray diffraction confirms the formation of single phase solid solution of BFO-BT. The structural change from rhombohedral to tetragonal is observed with MPB. Decrease in distortion of rhombohedral lattice is observed with BaTiO3 addition. All the samples show weak ferromagnetic behavior at room temperature due to a residual magnetic moment caused by canting spin magnetic structure having low coercivity and high saturation magnetization. The polar lattice of BiFeO3/BaTiO3 is retained throughout the solid solutions as observed from the polarization study. The ferroelectricity is observed throughout the solid solutions.

Chiral Structure in a Hard/Soft/Hard Layered Magnet

Micromagnetic simulation enabled us to fully characterize the nucleation and growth of buried domain walls in a layered hard/soft/hard ferromagnetic thin film. Simulation results show that the exchange spring trilayer exhibits a spiral spin magnetic structure and reveals detailed features of field-dependent domain walls evolution.