Neutron scattering studies of the cooperative paramagnet pyrochloreTb2Ti2O

Magnetic correlations in HoxTb2−xTiChang1, Schweika2, Kao3 et al. 2011Phys. Rev. BSelf Cite174140View full textAdd to dashboardCite

“…[6][7][8][9] Among the pyrochlore oxide family, Ho 2 Ti 2 O 7 , Ho 2 Sn 2 O 7 , Dy 2 Ti 2 O 7 , and Dy 2 Sn 2 O 7 have been identified as spin-ice materials and they can be modeled by a spin model with an 111 Ising-type anisotropy and a net ferromagnetic interaction. [6][7][8][9][10] Tb 2 Ti 2 O 7 is a fluctuating spin-liquid state at low temperature 5,[11][12][13][14] and, to date, there exists no model that can adequately describe all the physical properties observed in Tb 2 Ti 2 O 7 .…”

“…18,19 In Tb 2 Ti 2 O 7 , the system remains in a paramagnetic state, albeit sluggish, to temperatures as low as 15 mK, but shortrange (∼5Å) correlations develop below 100 K, which are characteristics associated with a cooperative paramagnetic or spin-liquid state. 5,12,14 The Curie-Weiss law fit through the high-temperature susceptibility of Tb 2 Ti 2 O 7 estimates the Tb 3+ moment of 9.6 μ B , almost the full free moment, and the Curie-Weiss temperature of −19 K. 12 Further studies on the Y diluted Tb 2 Ti 2 O 7 samples successfully estimated the interactions of the crystal field, dipolar, and exchange contributions to the Curie-Weiss temperature as −6, −2, and −11 K, respectively. 5 The Tb 3+ configuration was proposed as classical Ising spins constrained to point along local 111 directions with the mutual interactions of longer-range magnetic dipole interactions and near-neighbor antiferromagnetic exchange interactions.…”

“…5 The Tb 3+ configuration was proposed as classical Ising spins constrained to point along local 111 directions with the mutual interactions of longer-range magnetic dipole interactions and near-neighbor antiferromagnetic exchange interactions. 5,14 Neutron diffraction experiments revealed that the system has developed short-range antiferromagnetic correlations up to temperatures as high as 100 K, 12 which grow very little in range but increase in volume as the system cools. 20 Inelastic neutron scattering and heat-capacity measurements confirmed the first excited and ground states of the system, both doublets, are separated by about 18 K. 14 Heat capacity also reveals a T 2 dependence appropriate of a three-dimensional dynamical system.…”

Structural properties of the geometrically frustrated pyrochloreTb2Ti2OHan1, Gardner2, Booth3 2004Phys. Rev. BSelf Cite513320View full textAdd to dashboardCite

“…Tb 2 Ti 2 O 7 , on the other hand, appears to be the rare case of a pyrochlore that does not order magnetically, exhibiting a high degree of frustration (the large Tb 3+ moment has a Curie-Weiss temperature of ∼-19 K) down to 70 mK. 15,16,17 However, the pyrochlore system is also capable of producing a lattice with fairly subtle disorder that can precipitate a spin-glass phase, such as in the Mo-Mo near-neighbor pairs in Y The present work reports neutron powder diffraction (NPD) measurements of the average structure, and carefully considers the thermal dependence of the meansquared displacement parameters as a means of separating the non-Debye (presumably static) component of any positional disorder. In addition, the x-ray absorption fine-structure (XAFS) technique is used to check for disorder in the local environment around Tb and Ti atoms, and in particular for the kind of B-site correlated disorder that occurs in Y NRU reactor at Chalk River Laboratories.…”

Field-Induced Magnetic Order in Frustrated TbBaCo4O7Single Crystals

“…Probably the ground state of Tb 3+ is doublet with extremely anisotropic g-tensor in full analogy to the behavior of Tb 2 TiO 7 crystals (see e.g. [9]). The Ising-like character of Tb 3+ ions holds only at low temperature, because at higher temperatures a crossover to a Heisenberg-like behavior is expected since many crystal field levels become populated.…”