Dielectric and Magnetic Properties of Magnetically Frustrated R2Ti2O7 (R= Ho, Dy) Spin Ices
by Dr. Pramod Kumar Yadav (School of Materials Science & Technology, Indian Institute of Technology – (BHU), Varanasi)
Tuesday, January 28, 2020 from to (Asia/Kolkata)
Owing to the unusual geometry, frustrated magnets form exotic states that is quantum entangled and coherent over macroscopic length scale. Such phases offer promising perspectives for device applications in quantum information technologies, and their study can reveal new physics in quantum matters. Geometrically frustrated R2Ti2O7(R= Ho, Dy) spin ice materials are an appealing proposal of one such state, known for emergent gauge fields and fractional particle excitations phenomena. Present work focused to explore the quantum behavior, local probe of spin dynamics and magnetoelectricity in these materials. It has been found that at low temperature, electric behaviour emerges by local 3in-1out/1in-3out spin structure (magnetic monopole) induced electric dipoles via magnetostriction mechanism. Whereas, at higher temperature, crystal field anisotropy induced subtle change in oxygen position takes place, as observed in the form of dielectric relaxations. Density of magnetic monopole or electric dipoles can be probe by partial substitution of Fe spin at magnetic sites and control by external magnetic field. Further, a rigorous magnetic analysis has been done to classify the quantum critical region and signature of quantum correlations in these materials. Through H-T phase diagram, multiple quantum critical points are located. Further, a rigorous magnetic analysis has been done to classify the quantum critical region and signature of quantum correlations in these materials. Through H-T phase diagram, multiple quantum critical points are located. We have experimentally demonstrated the measurement protocol which set bounds on thermalization (responsible for classical behavior), and quantify the quantum correlation between the entangled spins. It has been found that external stimuli (frequency, field) exponentially dephase the quantum correlation of entangled spins. Observed anomalous sensitivity of quantum correlation on external stimuli (magnetic field and frequency), provides an effective tool to control the classical and quantum behavior of these materials. These findings show the diversity of frustrated quantum materials which needs to exploit for new technological revolution.