Spin-induced negative thermal expansion and spin–phonon coupling in van der Waals material CrBr3

Abstract The two-dimensional van der Waals (vdW) magnets retaining magnetic order in atomically thin limit demonstrate challenging physical phenomena and they are considered as prospective building blocks for construction of advanced spintronics nanoelectronics devices. Here, we present experimental evidence negative thermal expansion lattice volume vdW layers strong spin–phonon coupling effects, caused by formation the long-range ferromagnetic material CrBr 3 . neutron X-ray diffraction measurements revealed anomalous temperature variation parameters interatomic distances angles vicinity Curie ( T C ). A pronounced rise frequencies most observed vibrational modes unusual reversal broadening their full widths at half maximum below was found from Raman spectroscopy measurements.