High-pressure synthesis and characterization of the effective pseudospin<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>S</mml:mi><mml:mo>=</mml:mo><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:math>XY pyrochlores<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi mathvariant="normal">R</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi mathvariant="normal">P</mml:mi><mml:msub><mml:mi mathvariant="normal">t</mml:mi><mml:mn>2</mm

Cai, Yunqi; Qi, Caixia; Li, X.; Dun, Zhiling; Ma, Jie; Cruz, Clarina Dela; Jiao, Yuanyuan; Liao, Jing; Sun, Peijie; Li, Y. Q.; Zhou, Jingjing; Goodenough, John B.; Zhou, Haidong; Cheng, Jinguang

doi:10.1103/physrevb.93.014443

Cited by 23 publications

(31 citation statements)

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“…Each batch of Er 2 Pt 2 O 7 was x-rayed to verify phase purity and the total resultant sample was 1.2 grams. The room temperature lattice parameter (a = 10.13Å) and Curie-Weiss temperature (θ CW = −24.7 K [46]) for our sample are consistent with previous reports [14,47,48].…”

Section: Supplemental Material: Experimental Methodssupporting

confidence: 79%

“…Given that the lattice parameter of Er 2 Pt 2 O 7 differs by less then 0.5% from its titanate analog, it is surprising that the transition temperature is so substantially reduced. This dramatic reduction in T N occurs despite minimal structural modifications and a larger Curie-Weiss [12], Er2Ti2O7 [13], and Er2Pt2O7, filled in circles from [14] and open circles from our study. The latter two samples magnetically order with TN = 1.4 K and 1.2 K, respectively.…”

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confidence: 99%

“…Of these states, all but Γ 7 have been experimentally observed in the XY pyrochlores. This XY family is made up of In this Letter, we present a comprehensive neutron scattering study of Er 2 Pt 2 O 7 , a recent addition to the XY family of pyrochlores [5,14]. Through magnetic symmetry analysis, we find that Er 2 Pt 2 O 7 orders into the Γ 7 Palmer-Chalker state, the first XY pyrochlore shown to possess this ground state.…”

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confidence: 99%

“…Such observations eliminate simple energetic arguments for Er 2 Pt 2 O 7 's anomalously low T N . Two considerations are important to understand these surprising differences: (i) The partially occupied platinum 5d orbital can facilitate superexchange pathways that are inaccessible in closed shell titanium [14,37], and (ii) The XY pyrochlores live in a rich phase space where modest changes in anisotropic exchange parameters can have a large effect on ground state selection [8]. Indeed, this paradigm predicts that proximity to competing classical phases should manifest as a suppressed ordering temperature [8].…”

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confidence: 99%

“…Furthermore, bulk characterization indicates the ordered state of Er 2 Pt 2 O 7 is antiferromagnetic [14], and Γ 9 is ferromagnetic. Thus, on qualitative grounds alone, one could deduce that Er 2 Pt 2 O 7 orders into the Γ 7 irreducible representation.…”

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Phase Competition in the Palmer-Chalker XY Pyrochlore Er2Pt2O<

et al. 2017

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We report neutron scattering measurements on Er2Pt2O7, a new addition to the XY family of frustrated pyrochlore magnets. Symmetry analysis of our elastic scattering data shows that Er2Pt2O7 is the first XY pyrochlore to order into the k = 0, Γ7 magnetic structure (the Palmer-Chalker state), at TN = 0.38 K. This contrasts with its sister XY pyrochlore antiferromagnets Er2Ti2O7 and Er2Ge2O7, both of which order into Γ5 magnetic structures at much higher temperatures, TN = 1.2 K and 1.4 K, respectively. In this temperature range, the magnetic heat capacity of Er2Pt2O7 contains a broad anomaly centered at T * = 1.5 K. Our inelastic neutron scattering measurements reveal that this broad heat capacity anomaly sets the temperature scale for strong short-range spin fluctuations. Below TN = 0.38 K, Er2Pt2O7 displays a gapped spin wave spectrum with an intense, flat band of excitations at lower energy and a weak, diffusive band of excitations at higher energy. The flat band is well-described by classical spin wave calculations, but these calculations also predict sharp dispersive branches at higher energy, a striking discrepancy with the experimental data. This, in concert with the strong suppression of TN , is attributable to enhanced quantum fluctuations due to phase competition between the Γ7 and Γ5 states that border each other within a classically predicted phase diagram.The low temperature magnetism of the rare-earth pyrochlore oxides, R 2 B 2 O 7 , has become synonymous with complexity and exotic ground states. Both of these are natural consequences of magnetism on the pyrochlore lattice, which is comprised of two site-ordered networks of corner-sharing tetrahedra. This is the canonical threedimensional crystalline architecture for geometric magnetic frustration, in which competing interactions can preclude or hinder the formation of a classically ordered state. The diversity in the phenomenology of the rare-earth pyrochlores is attributable to the different anisotropies and interactions exhibited by the rare-earth ions that can occupy its magnetic sublattice, which conspire to produce a veritable zoo of magnetic behaviors [1].A particularly interesting sub-group of the rare-earth pyrochlores are those that exhibit XY spin anisotropy [2], which is obtained when the rare-earth site is occupied by either erbium (Er) or ytterbium (Yb). This XY label is garnered on the basis of their crystal electric field phenomenology, where in both cases, the ground state is an isolated doublet protected by Kramers' theorem, allowing an effective S = 1 /2 description [3-5]. The anisotropic exchange Hamiltonian, with a form determined by the symmetry of the crystal lattice, provides an appropriate starting point for understanding the ground states of many XY pyrochlores [6][7][8]. Within the nearest neighbor version of this model, certain sets of exchange parameters can give rise to exotic states such as quantum spin ice [6,9] or various spin liquids [10,11], while other sets of exchange parameters are predicted to stabilize classica...

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Section: Supplemental Material: Experimental Methodssupporting

confidence: 79%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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