Co-existence of relaxor behaviour and ferroelectric order due to interplay of lattice and dipoles in a triangular lattice antiferromagnet P

Our comprehensive study on a layered triangular lattice antiferromagnet BiCrTeO6 using the magnetization (M), specific heat (Cp), dielectric (e'), synchrotron x-ray diffraction, and neutron diffraction measurements divulged two successive antiferromagnetic transitions occurring at TN1 ~16 K and TN2 ~10.5 K, where TN2 refers to a complex helical and elliptical cycloidal antiferromagnetic spin ordering, which triggers a spectrum of intriguing phenomena, including a pronounced magnetodielectric effect, and a spin-driven ferroelectric order at TN2. Moreover, a higher temperature (T >30 K) dielectric relaxor behavior is also observed . The present system belongs to trigonal structure with crystal symmetry P-31c (300 K), which is centrosymmetric in nature. Hence, a crucial step is to investigate the low-temperature crystal structure via synchrotron X-ray diffraction (XRD), particularly below TN2, to elucidate the development of ferroelectric order.