Magnetodielectric Relaxation in Ho2Ti2O7 and Dy2Ti2O7 Spin Ice

Yadav, Pramod Kumar; Upadhyay, Chandan

doi:10.1007/s10948-018-4957-4

Cited by 5 publications

(5 citation statements)

References 34 publications

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“…Hence the dominance of CF effect below 30 K could be responsible for this distinct low temperature behaviour [39]. Similar behaviour in thermal expansion has also been observed in Ho 2 Ti 2 O 7 spin ice system using SXRD measurement [40]. A possible multipolar phase spontaneously breaking of rotational symmetry while preserving translational invariance has been reported in case of Cd 2 Re 2 O 7 pyrochlore near 200 K [41].…”

Section: Resultssupporting

confidence: 70%

Robust spin-ice freezing in magnetically frustrated Ho₂Ge_xTi_2−xO₇pyrochlore

Shukla¹,

Upadhyay²,

Tolkiehn³

et al. 2020

J. Phys.: Condens. Matter

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Structural analysis of spin frustrated Ho 2 Ge x Ti 2−x O 7 (x = 0, 0.1, 0.15 & 0.25) pyrochlore oxides has been performed using high resolution x-ray diffraction pattern and low temperature synchrotron x-ray diffraction pattern. The effect of positive chemical pressure on the spin dynamics of Ho 2 Ge x Ti 2−x O 7 has been analysed through the study of static (M-T and M-H; magnetisation against temperature & magnetisation against magnetic field) and dynamical (ac susceptibility) magnetic measurements. In lower temperature regime (∼2 K), such systems are predominantly governed by competing exchange (J nn ) and dipolar (D nn ) magnetic interactions. Magnetic measurements indicate that the application of increased chemical pressure in Ho 2 Ti 2 O 7 matrix propels the system towards diminished ferromagnetic interaction. Dipolar coupling constant remains almost unchanged but Curie-Weiss temperature (θ cw ) reduces to −0.04 K from 0.33 K (for an applied magnetic field; H = 100 Oe) with increasing x in Ho 2 Ge x Ti 2−x O 7 . Positive chemical pressure establishes the dominance of Ho-Ho antiferromagnetic interaction J nn over dipolar interaction D nn . Spin relaxation feature corresponding to thermally activated single ion freezing (T s ∼ 15 K) is shifted towards lower temperature. This chemical pressure-driven T s shift is ascribed to the alteration in crystal field effect, which reduces the activation energy for singe ion spin freezing. The reduction in the activation energy indicates crystal field-phonon coupling in Ho 2 Ge x Ti 2−x O 7 system. The robustness in spin ice freezing (second spin relaxation feature in ac susceptibility curve) remains unaffected with increasingly chemical pressure. This spin freezing ('2 in-2 out' spin arrangement in tetrahedra) is related to quantum tunnelling phenomenon, at T ice ∼ 2 K. It indicates that majority of spins still follows the 'ice rule' in Ho 2 Ge x Ti 2−x O 7 even after the application of chemical pressure.

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Section: Resultssupporting

confidence: 70%

Robust spin-ice freezing in magnetically frustrated Ho₂Ge_xTi_2−xO₇pyrochlore

Shukla¹,

Upadhyay²,

Tolkiehn³

et al. 2020

J. Phys.: Condens. Matter

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“…For higher magnetic field, ∆χ ′ (H) do not show any crossover and exhibits a linear behavior with temperature. The observed temperature and magnetic field sweep rate dependence of anomalous hysteresis indicates that the existing phonon-mediated spin-flipping mechanism [25][26][27][28] gets altered by biased H dc . For investigation, we performed the temperature-and magnetic field-dependent dielectric permittivity (ε) measurement for DTO.…”

Section: Figures 1(a) and (B)mentioning

confidence: 99%

Emergence of field-induced memory effect in spin ices

Yadav,

Upadhyay,

Kumar

et al. 2023

J. Phys.: Condens. Matter

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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.

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“…Notably, the decrease in the % MDC in the x = 0.15 sample is smaller than the x = 0.05 sample, suggesting the strengthening in the positive magnetodielectric coupling at higher Fe concentration. The spontaneous increase in the %MDC in the x = 0 sample shows the development of magnetic field-induced strain in the lattice by underlying spin-phonon coupling [32,[35][36][37][38]. Due to this coupling, the field-induced quenched spin sites produce a strain in the lattice more prominently up to ∼0.2 T. The transition in %MDC from positive to negative and its gradual decrease with the magnetic field signifies the suppression in the existing magneto-dielectric coefficient in Fe-substituted compositions.…”

Section: Resultsmentioning

confidence: 95%

“…The inhibitory effect of Fe substitution on the crossover in cyclic χ′(H) (figure 5(b)) shows its distinct nature of spin, which remains quenched even at a very small magnetic field. This inhibitory effect is either purely associated with quenched spin sites or a cumulative effect associated with quenched spin sites and magneto-dielectric coupling [16,[31][32][33]. For the investigation, we have conducted the temperature and magnetic field-dependent dielectric measurements on DFTO at different DC bias magnetic fields, shown in figure S2 in the supplementary file.…”

Section: Resultsmentioning

confidence: 99%

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

Yadav,

Upadhyay,

Kumar

et al. 2024

Phys. Scr.

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The study of defect-induced effects in functional materials is high-priority research for the miniaturization of smart devices. To elucidate the influence of local defects stemming from intrinsic or extrinsic factors on the enigmatic behavior of cooperative spin dynamics, we investigated the Dy2-xFexTi2O7 compound within a narrow Fe substitution range (x = 0–0.15). Our experimental findings unequivocally demonstrate that the dynamic response of cooperative spins and the emergence of anomalous memory effect are intricately linked to local defects. Depending on the nature and dynamics of these defects, the dynamic response of cooperative spins undergoes alteration. Notably, observed anomalous effect becomes more pronounced in scenarios characterized by slower defect dynamics and when cooperative spins are further from equilibrium. The emergence and sensitivity of thermomagnetic hysteresis (memory effect) to cooperative spin dynamics and external stimuli underscore the richness of Dy2Ti2O7 as a material for captivating physics investigations.

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Magnetodielectric Relaxation in Ho2Ti2O7 and Dy2Ti2O7 Spin Ice

Cited by 5 publications

References 34 publications

Robust spin-ice freezing in magnetically frustrated Ho₂Ge_xTi_2−xO₇pyrochlore

Robust spin-ice freezing in magnetically frustrated Ho₂Ge_xTi_2−xO₇pyrochlore

Emergence of field-induced memory effect in spin ices

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

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Magnetodielectric Relaxation in Ho2Ti2O7 and Dy2Ti2O7 Spin Ice

Cited by 5 publications

References 34 publications

Robust spin-ice freezing in magnetically frustrated Ho2GexTi2−xO7pyrochlore

Robust spin-ice freezing in magnetically frustrated Ho2GexTi2−xO7pyrochlore

Emergence of field-induced memory effect in spin ices

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

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Robust spin-ice freezing in magnetically frustrated Ho₂Ge_xTi_2−xO₇pyrochlore

Robust spin-ice freezing in magnetically frustrated Ho₂Ge_xTi_2−xO₇pyrochlore

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