by Nag, A., Bhowal, S., Sala, M. Moretti, Efimenko, A. and Dasgupta, I and Ray, Sugata
Abstract:
Investigation of elementary excitations has advanced our understanding of many-body physics governing most physical properties of matter. Recently spin-orbit excitons have drawn much attention, whose condensates near phase transitions exhibit Higgs mode oscillations, a long-sought-after physical phenomenon [A. Jain, et al., Nat. Phys. 13, 633 (2017)]. These critical transition points, resulting from competing spin-orbit coupling (SOC), local crystalline symmetry, and exchange interactions, are not obvious in iridium-based materials, where SOC prevails in general. Here, we present results of resonant inelastic x-ray scattering on a spin-orbital liquid Ba3ZnIr2O9 and three other 6H-hexagonal perovskite iridates that show magnetism, contrary to the nonmagnetic singlet ground state expected due to strong SOC. Our results show that substantial hopping between closely placed Ir5+ ions within Ir2O9 dimers in these 6H iridates modifies spin-orbit coupled states and reduces spin-orbit excitation energies. Here, we are forced to use at least a two-site model to match the excitation spectrum going in-line with the strong intradimer hopping. Apart from SOC, low-energy physics of iridates is thus critically dependent on hopping and may not be ignored even for systems havingmoderate hopping, where the excitation spectra can be explained using an atomic model. SOC, which is generally found to be 0.4-0.5 eV in iridates, is scaled in effect down to similar to 0.26 eV for the 6H systems, sustaining the hope of achieving quantum criticality by tuning Ir-Ir separation.
Reference:
Hopping-Induced Ground-State Magnetism in 6H Perovskite Iridates (Nag, A., Bhowal, S., Sala, M. Moretti, Efimenko, A. and Dasgupta, I and Ray, Sugata), In PHYSICAL REVIEW LETTERS, AMER PHYSICAL SOC, volume 123, 2019.
Bibtex Entry:
@article{ ISI:000473311400013, Author = {Nag, A. and Bhowal, S. and Sala, M. Moretti and Efimenko, A. and Dasgupta, I and Ray, Sugata}, Title = {{Hopping-Induced Ground-State Magnetism in 6H Perovskite Iridates}}, Journal = {{PHYSICAL REVIEW LETTERS}}, Year = {{2019}}, Volume = {{123}}, Number = {{1}}, Month = {{JUL 1}}, Abstract = {{Investigation of elementary excitations has advanced our understanding of many-body physics governing most physical properties of matter. Recently spin-orbit excitons have drawn much attention, whose condensates near phase transitions exhibit Higgs mode oscillations, a long-sought-after physical phenomenon {[}A. Jain, et al., Nat. Phys. 13, 633 (2017)]. These critical transition points, resulting from competing spin-orbit coupling (SOC), local crystalline symmetry, and exchange interactions, are not obvious in iridium-based materials, where SOC prevails in general. Here, we present results of resonant inelastic x-ray scattering on a spin-orbital liquid Ba3ZnIr2O9 and three other 6H-hexagonal perovskite iridates that show magnetism, contrary to the nonmagnetic singlet ground state expected due to strong SOC. Our results show that substantial hopping between closely placed Ir5+ ions within Ir2O9 dimers in these 6H iridates modifies spin-orbit coupled states and reduces spin-orbit excitation energies. Here, we are forced to use at least a two-site model to match the excitation spectrum going in-line with the strong intradimer hopping. Apart from SOC, low-energy physics of iridates is thus critically dependent on hopping and may not be ignored even for systems havingmoderate hopping, where the excitation spectra can be explained using an atomic model. SOC, which is generally found to be 0.4-0.5 eV in iridates, is scaled in effect down to similar to 0.26 eV for the 6H systems, sustaining the hope of achieving quantum criticality by tuning Ir-Ir separation.}}, Publisher = {{AMER PHYSICAL SOC}}, Address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, Type = {{Article}}, Language = {{English}}, Affiliation = {{Nag, A; Ray, S (Corresponding Author), Indian Assoc Cultivat Sci, Sch Mat Sci, Kolkata 700032, India. Nag, A.; Ray, Sugata, Indian Assoc Cultivat Sci, Sch Mat Sci, Kolkata 700032, India. Bhowal, S.; Dasgupta, I, Indian Assoc Cultivat Sci, Sch Phys Sci, Kolkata 700032, India. Sala, M. Moretti; Efimenko, A., ESRF European Synchrotron, 71 Ave Martyrs, F-38000 Grenoble, France. Sala, M. Moretti, Politecn Milan, Dipartimento Fis, Piazza Leonardo da Vinci 32, I-20133 Milan, Italy. Nag, A., Diamond Light Source, Harwell Campus, Didcot OX11 0DE, Oxon, England. Bhowal, S., Univ Missouri, Dept Phys & Astron, Columbia, MO 65211 USA.}}, DOI = {{10.1103/PhysRevLett.123.017201}}, Article-Number = {{017201}}, ISSN = {{0031-9007}}, EISSN = {{1079-7114}}, Research-Areas = {{Physics}}, Web-of-Science-Categories = {{Physics, Multidisciplinary}}, Author-Email = {{mssr@iacs.res.in}}, ResearcherID-Numbers = {{Moretti, Marco/AAF-9255-2019 }}, ORCID-Numbers = {{Moretti, Marco/0000-0002-9744-9976 Nag, Abhishek/0000-0002-1394-5105}}, Funding-Acknowledgement = {{Department of Science and Technology (DST)Department of Science & Technology (India) {[}WTI/2K15/74]; UGCDAE Consortium for Scientific Research, Mumbai, India {[}CRS-M-286]; Science and Engineering Research Board (SERB), IndiaDepartment of Science & Technology (India)Science Engineering Research Board (SERB), India {[}EMR/2016/005925]}}, Funding-Text = {{S. R. and I. D. G. thank the Technical Research Center of IACS. S. R. also thanks the Department of Science and Technology (DST) (Project No. WTI/2K15/74), UGCDAE Consortium for Scientific Research, Mumbai, India (Project No. CRS-M-286) for support, and Jawaharlal Nehru Centre for Advanced Scientific Research from the DST-Synchrotron-Neutron project, for performing experiments at ESRF (Proposal No. HC-2872). A. N. thanks M. P. M. Dean for useful comments about the result. I. D. G. thanks Science and Engineering Research Board (SERB), India (Project No. EMR/2016/005925) for support.}}, Number-of-Cited-References = {{31}}, Times-Cited = {{2}}, Usage-Count-Last-180-days = {{2}}, Usage-Count-Since-2013 = {{18}}, Journal-ISO = {{Phys. Rev. Lett.}}, Doc-Delivery-Number = {{IF8BC}}, Unique-ID = {{ISI:000473311400013}}, DA = {{2020-12-22}}, }
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