Experimental signatures of a three-dimensional quantum spin liquid in effective spin-1/2 Ce2Zr2O7 pyrochlore

• Published in: arXiv.org 2019-09
• Main Authors: Gao, Bin, Chen, Tong, Tam, David W, Chien-Lung, Huang, Sasmal, Kalyan, Adroja, Devashibhai T, Ye, Feng, Cao, Huibo, Sala, Gabriele, Stone, Matthew B, Baines, Christopher, Barker, Joel A T, Hu, Haoyu, Jae-Ho, Chung, Xu, Xianghan, Cheong, Sang-Wook, Manivannan Nallaiyan, Spagna, Stefano, Maple, M Brian, Nevidomskyy, Andriy H, Morosan, Emilia, Chen, Gang, Dai, Pengcheng
• Format: Article
• Language: English
• Subjects: Cerium; Condensed matter physics; Electron spin; Excitation; Muon spin relaxation; Neutron diffraction; Neutron scattering; Neutrons; Organic chemistry; Pyrochlores; Single crystals; Spin liquid; Superconductivity; Transition temperature
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1901.10092

A quantum spin liquid (QSL) is a state of matter where unpaired electrons' spins in a solid are quantum entangled, but do not show magnetic order in the zero-temperature limit. Because such a state may be important to the microscopic origin of high-transition temperature superconductivity and useful for quantum computation, the experimental realization of QSL is a long-sought goal in condensed matter physics. Although neutron scattering experiments on the two-dimensional (2D) spin-1/2 kagome-lattice ZnCu3(OD)6Cl2 and effective spin-1/2 triangular lattice YbMgGaO4 have found evidence for a continuum of magnetic excitations, the hallmark of a QSL carrying 'fractionalized quantum excitations', at very low temperature, magnetic and nonmagnetic site chemical disorder complicates the interpretation of the data. Recently, the three-dimensional (3D) Ce3+ pyrochlore lattice Ce2Sn2O7 has been suggested as a clean, effective spin-1/2 QSL candidate, but there is no evidence of a spin excitation continuum. Here we use thermodynamic, muon spin relaxation ({\mu} SR), and neutron scattering experiments on single crystals of Ce2Zr2O7, a compound isostructural to Ce2Sn2O7, to demonstrate the absence of magnetic ordering and the presence of a spin excitation continuum at 35 mK, consistent with the expectation of a QSL. Since our neutron diffraction and diffuse scattering measurements on Ce2Zr2O7 reveal no evidence of oxygen deficiency and magnetic/nonmagnetic ion disorder as seen in other pyrochlores, Ce2Zr2O7 may be the first example of a 3D QSL material with minimum magnetic and nonmagnetic chemical disorder.