Emergent order in the spin-frustrated systemDyxTb2−xTi2O7

Abstract

We report the a.c. susceptibility study of DyxTb2−xTi2O7 with x ∈ [0, 2]. In addition to the single-ion effect at Ts (single-ion effect peak temperature) corresponding to the Dy 3+ spins as that in spin ice Dy2Ti2O7 and a possible spin freezing peak at T f (T f < 3 K), a new peak associated with Tb 3+ is observed in χac(T ) at nonzero magnetic field with a characteristic temperature T * (T f < T * < Ts). T * increases linearly with x in a wide composition range (0 < x < 1.5 at 5 kOe). Both application of a magnetic field and increasing doping with Dy 3+ enhance T * . The T * peak is found to be thermally driven with an unusually large energy barrier as indicated from its frequency dependence. These effects are closely related to the crystal field levels, and the underlying mechanism remains to be understood.

High temperature spin-freezing transition in pyrochlore Eu2Ti2O7: A new observation from ac-susceptibility

“…But for Dy 2 Ti 2 O 7 , an additional unexpected peak in ac susceptibility at ̴ 16K is found, which is absent in spin ice Ho 2 Ti 2 O 7 suggesting a strange difference between these compounds [10,12]. This spin freezing at T=16K >T ice is attributed to the single spin freezing process [12,[19][20][21][22][23]. The ice freezing (<4K) and this 16K single ion freezing are inter-linked by quantum tunnelling process (which is characterized by a very weak temperature dependence of spin relaxation times thus showing a plateau region below 12K) through the CF barrier and this is explained by creation and propagation of monopoles [19,24].…”

Nonmonotonic residual entropy in diluted spin ice: A comparison between Monte Carlo simulations of diluted dipolar spin ice models and experimental results

“…For example, direct 48 and indirect 49 evidence has recently been put forward that, in image furnace grown single crystals, there is a small level (O(1%)) of substitution of the Ti 4+ transition metal ions by trivalent rare-earth ions − a phenomenon referred to as "stuffing". Other examples include the mixing of different types of ions on the rare-earth site 50 or different non-magnetic ions at the B site. 51,52 Thus, in comparison with these various disorder settings, which would all generate random bonds, the problem of site-dilution may be expected to be simpler, and a necessary first step in our goal of understanding the effects of random disorder in magnetic pyrochlores oxides.…”

Experimental observation of magnetoelectricity in spin ice Dy2Ti2O7

“…No spin freezing behavior is observed within the selected frequencies at zero magnetic field. However, the imaginary part of susceptibility shows a sharp increase at low temperature, which indicates a strongly dissipative process occurs below 2 K [48]. When the magnetic field increases to 1 Tesla, two clear dips at 3 K, 13 K emerge, identified as T f , T * , respectively.…”