27Al-NMR Study on a square-Kagome lattice antiferromagnet

NMR study has been performed on an S = 1/2 antiferromagnet KCu6AlBiO4(SO4)5Cl on the square-Kagome lattice, which has three slightly inequivalent nearest-neighbor interactions. Because of the geometrical frustration inherited from triangles within the square kagome lattice and of the low dimensionality, a long range magnetic order is strongly suppressed; its absence has so far been confirmed in low temperatures down to dilution refrigerator region. 27Al-NMR spectra and the longitudinal relaxation time T1 were measured by a conventional pulsed spectrometer on powder sample under several magnetic fields between 3 and 10 T and in low temperatures down to 0.35 K. The NMR line width due to the inhomogeneous broadening increased with lowering temperatures and leveled off below 3 K, where FWHM reached the value as large as 0.1 T, implying that the ground state is magnetic one, consistent with previous reports. On the other hand, the longitudinal nuclear spin relaxation rate 1/T1 obeyed the Arrhenius law with the thermal activation energy {\Delta} = 2K at low temperatures, suggesting that a small gap is formed in the spin excitation spectrum.Comment: Hyperfine Interaction 2023, to appear in Interaction

Atomic reconstruction induced by uniaxial stress in MnP

Abstract In condensed matter physics, pressure is frequently used to modify the stability of both electronic states and atomic arrangements. Under isotropic pressure, the intermetallic compound MnP has recently attracted attention for the interplay between pressure-induced superconductivity and complicated magnetic order in the vicinity . By contrast, we use uniaxial stress, a directional type of pressure, to investigate the effect on the magnetism and crystal structure of this compound. An irreversible magnetisation response induced by uniaxial stress is discovered in MnP at uniaxial stress as low as $$0.04\ \text {GPa}$$ 0.04 GPa . Neutron diffraction experiments reveal that uniaxial stress forms crystal domains that satisfy pseudo-rotational symmetry unique to the MnP-type structure. The structure of the coexisting domains accounts for the stress-induced magnetism. We term this first discovered phenomenon atomic reconstruction (AR) induced by uniaxial stress. Furthermore, our calculation results provide guidelines on the search for AR candidates. AR allows crystal domain engineering to control anisotropic properties of materials, including dielectricity, elasticity, electrical conduction, magnetism and superconductivity. A wide-ranging exploration of potential AR candidates would ensure that crystal domain engineering yields unconventional methods to design functional multi-domain materials for a wide variety of purposes