Dipolar Spin Ice States with a Fast Monopole Hopping Rate in CdEr_{2}X_{4} (X=Se, S).

Autor:	Gao S; Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.; Department of Quantum Matter Physics, University of Geneva, CH-1211 Geneva, Switzerland., Zaharko O; Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland., Tsurkan V; Experimental Physics V, University of Augsburg, D-86135 Augsburg, Germany.; Institute of Applied Physics, Academy of Sciences of Moldova, MD-2028 Chisinau, Republic of Moldova., Prodan L; Institute of Applied Physics, Academy of Sciences of Moldova, MD-2028 Chisinau, Republic of Moldova., Riordan E; School of Physics and Astronomy, Cardiff University, CF24 3AA Cardiff, United Kingdom., Lago J; Department of Inorganic Chemistry, Universidad del País Vasco (UPV-EHU), 48080 Bilbao, Spain., Fåk B; Institut Laue-Langevin, CS 20156, 38042 Grenoble Cedex 9, France., Wildes AR; Institut Laue-Langevin, CS 20156, 38042 Grenoble Cedex 9, France., Koza MM; Institut Laue-Langevin, CS 20156, 38042 Grenoble Cedex 9, France., Ritter C; Institut Laue-Langevin, CS 20156, 38042 Grenoble Cedex 9, France., Fouquet P; Institut Laue-Langevin, CS 20156, 38042 Grenoble Cedex 9, France., Keller L; Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland., Canévet E; Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.; Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark., Medarde M; Laboratory for Scientific Developments and Novel Materials, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland., Blomgren J; RISE Acreo AB, SE-411 33 Göteborg, Sweden., Johansson C; RISE Acreo AB, SE-411 33 Göteborg, Sweden., Giblin SR; School of Physics and Astronomy, Cardiff University, CF24 3AA Cardiff, United Kingdom., Vrtnik S; Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia., Luzar J; Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia., Loidl A; Experimental Physics V, University of Augsburg, D-86135 Augsburg, Germany., Rüegg C; Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.; Department of Quantum Matter Physics, University of Geneva, CH-1211 Geneva, Switzerland., Fennell T; Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
Jazyk:	angličtina
Zdroj:	Physical review letters [Phys Rev Lett] 2018 Mar 30; Vol. 120 (13), pp. 137201.
DOI:	10.1103/PhysRevLett.120.137201
Abstrakt:	Excitations in a spin ice behave as magnetic monopoles, and their population and mobility control the dynamics of a spin ice at low temperature. CdEr_{2}Se_{4} is reported to have the Pauling entropy characteristic of a spin ice, but its dynamics are three orders of magnitude faster than the canonical spin ice Dy_{2}Ti_{2}O_{7}. In this Letter we use diffuse neutron scattering to show that both CdEr_{2}Se_{4} and CdEr_{2}S_{4} support a dipolar spin ice state-the host phase for a Coulomb gas of emergent magnetic monopoles. These Coulomb gases have similar parameters to those in Dy_{2}Ti_{2}O_{7}, i.e., dilute and uncorrelated, and so cannot provide three orders faster dynamics through a larger monopole population alone. We investigate the monopole dynamics using ac susceptometry and neutron spin echo spectroscopy, and verify the crystal electric field Hamiltonian of the Er^{3+} ions using inelastic neutron scattering. A quantitative calculation of the monopole hopping rate using our Coulomb gas and crystal electric field parameters shows that the fast dynamics in CdEr_{2}X_{4} (X=Se, S) are primarily due to much faster monopole hopping. Our work suggests that CdEr_{2}X_{4} offer the possibility to study alternative spin ice ground states and dynamics, with equilibration possible at much lower temperatures than the rare earth pyrochlore examples.
Databáze:	MEDLINE
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