Emergence of field-induced memory effect in spin ices

Abstract

Out-of-equilibrium investigation of strongly correlated materials deciphers the hidden equilibrium properties. Herein, we have investigated the out-of-equilibrium magnetic properties of polycrystalline Dy2Ti2O7 and Ho2Ti2O7 spin ices. Our experimental findings reveal the emergence of magnetic field-induced anomalous hysteresis observed solely in temperature-and magnetic field-dependent AC susceptibility measurements. The observed memory effect (anomalous thermomagnetic hysteresis) exhibits a strong dependence on both thermal and non-thermal driving variables. Owing to the non-collinear spin structure, the applied DC bias magnetic field produces quenched disorder sites in the cooperative Ising spin matrix and suppresses the spin-phonon coupling. These quench disorders create a dynamic spin correlation, having slow spin relaxation and quick decay time, which additionally contribute to AC susceptibility. The initial conditions and measurement protocol decide the magnitude and sign of this dynamical term contributing to AC susceptibility. It is being suggested that such out-of-equilibrium properties arise from the combined influences of geometric frustration, disorder, and the cooperative nature of spin dynamics exhibited by these materials.

Influence of local defects in the generation of memory effect in Dy2Ti2O7 compound: Fe-doped study

“…Within the M(T) profile, a thermal hysteresis emerges below 4 K in FCC and FCW measurement modes for all the samples. Unlike the behaviors seen in spin glasses, where thermal hysteresis becomes evident in ZFCW and FCW measurements, we did not find any hysteresis in ZFCW and FCW measurements [19]. Previous studies reported a liquid-gas-type transition associated with the change in the local spin structure for DTO [25,26].…”

“…A recent study further uncovers the field-induced memory effect observed in temperature and magnetic field-dependent AC susceptibility χ(T, H) measurements of DTO. This effect was observed in both powder and pellet samples, confirming its intrinsic origin [19,20]. Experimental results suggest that generating field-induced random quenched spin defects plays a crucial role in the behavior of cooperative spin dynamics.…”

“…In figure 1(b), M(T) characteristics of DFTO depicted under zero field-cooled warming mode (ZFCW), fieldcooled cooling mode (FCC), and field-cooled warming mode (FCW) conditions at 0.6 T DC bias magnetic field (H dc ). For the x = 0 sample, our previously reported data was employed [19]. As observed in M(H), M(T) also shows a reduction in magnetization with increasing Fe concentration in DFTO.…”

“…For the x = 0 sample, previous investigations demonstrated the exponential decaying behavior of Δχ′(T) with increasing amplitude and frequency variables [19,20]. To investigate the impact of Fe substitution on the exponential decay behavior of Δχ′(T) with frequency, we performed χ(T) measurements on DFTO at 0.6 T H dc for different frequencies, depicted as figure 4.…”

“…Magnetic fielddependent AC susceptibility measurements at different temperatures and frequencies were performed @100 Oe sec −1 continuous sweep rate. Low-temperature magneto-dielectric measurements of DFTO were performed as mentioned in [19] condition, using an Agilent E4980A LCR meter interfaced with the Physical Properties Measurement System (PPMS-3)® (Evercool Quantum Design, Inc.) USA.…”