Magnetic Field Induced Transitions from Spin Glass to Liquid to Long Range Order in a 3D Geometrically Frustrated Magnet

Quantum Criticality in an Organic Magnet

“…This provides an estimate for exchange anisotropy of 0:1 meV [33], which could lead to an Ising transition at sufficiently low T. Alternatively nuclear spins and phonons which are effectively decoupled from magnetism at high T and normally unimportant compared to exchange interactions at low T may become relevant close to the field tuned QCP. Similar low T anomalies have been found in other electronic spin systems close to quantum criticality such as GGG [34], LiHoF 4 [10], and ZnCr 2 O 4 [35]. In LiHoF 4 , the anomaly favors the spin ordered phase and is associated with hyperfine coupling to the nuclear spin system.…”

Magnetothermal study of a Dy-stuffed spin ice:Dy2(DyxTi2−x)Ueland1, Lau2, Freitas3 et al. 2008Phys. Rev. BSelf Cite15140View full textAdd to dashboardCite

“…(GGG), showing a broad peak at higher temperatures, which was found to correspond to the quenching of local antiferromagnetic correlations [7]. The two peaks which evolve at lower temperatures are also reminiscent of the (much sharper) peaks associated with field-induced long range order in that material [9].…”

“…(GGG), showing a broad peak at higher temperatures, which was found to correspond to the quenching of local antiferromagnetic correlations [7]. The two peaks which evolve at lower temperatures are also reminiscent of the (much sharper) peaks associated with field-induced long range order in that material [9].Since the susceptibility is so similar in the Ho and Dy SSI materials, the question arises of why the entropy is so different, i.e., why there is no measurable macroscopic zero point entropy in the Dy material. A possible explanation is that the dissimilarity in the entropy data arises from the differences in the structural domains of local pyrochlore order.…”

“…The energy scales of the interactions in these magnets offer unique opportunities to study how frustrated thermodynamic systems settle into their lowest energy states [1,2,3]. Examples of novel ground states observed in geometrically frustrated magnets include spin-glass-like states despite the presence of minimal structural disorder [4,5,6,7], cooperative paramagnetic states, in which the spins are locally correlated yet continue to fluctuate as T ~ 0 [8,9,10,11], and spin ice states [12,13,14,15,16,17,18,19,20,21], in which the spins freeze into a state analogous to that of the protons in frozen water. In this paper we report experimental results for variants of two spin ice materials, formed by increasing the density of spins present in the materials.…”

Metamagnetic behaviour and effect of field cooling on sharp magnetization jumps in multiferroic Y 2 CoMnO 6

“…Recently, metamagnetic behaviour has also been reported in some of the well known multiferroic systems such as BiFeO 3 and phase separated multiferroic Eu 1-x Y x MnO 3 (x=0.2, 0.25) systems; interestingly, a coupling between metamagnetic behaviour and ferroelectric polarization with the external magnetic field has been noticed [12][13][14]. Though the exact origin of this effect is unclear, several mechanisms have been proposed in different systems, such as the field dependent orbital ordering in Pr 0.5 Ca 0.5 Mn 0.95 Co 0.05 O 3 [15], martensitic like transformation associated with interface strains in phase separated systems [9][10][11]16], spin quantum transition in Pr 5/8 Ca 3/8 MnO 3 [17], geometric frustration in garnets [18], spin reorientation in FeRh thin films [2] and magnetic field induced spin flop transition in Ca 3 CoMnO 6 [19]. In charge ordered manganite systems, the field induced magnetization irreversibility with first order nature was assigned to the intrinsic magnetic phase separation, i.e., the coexistence of competing magnetic phases in micro/nano length scales [20], where avalanche-like growth of FM clusters in the vicinity of critical magnetic field (H C ) lead to sharp changes in magnetization.…”