| 1. |
- Bhowal, S., et al.
(författare)
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Development of collective structures over noncollective excitations in Nd-139
- 2011
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 84:2
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states in Nd-139 were investigated using the reaction Zr-96(Ca-48,5n) at a beam energy of 195 MeV and gamma-ray coincidences were acquired with the Euroball spectrometer. Apart from several dipole bands at medium excitation energy, three quadrupole bands have been observed at high spin. Linking transitions connecting two of the high-spin bands to low-energy states have been observed. Calculations based on the cranked-Nilsson-Strutinsky formalism have been used to assign configurations for the high-spin quadrupole bands.
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| 2. |
- Panda, S. K., et al.
(författare)
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Electronic structure and spin-orbit driven magnetism in d(4.5) insulator Ba3YIr2O9
- 2015
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 92:18
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Tidskriftsartikel (refereegranskat)abstract
- We have carried out a detailed first-principles study of a d(4.5) quaternary iridate Ba3YIr2O9 both in its 6H-perovskite- type ambient pressure (AP) phase and also for the high pressure (HP) cubic phase. Our analysis reveals that the AP phase belongs to the intermediate spin-orbit coupling (SOC) regime. This is further supported by the identification of the spin moment as the primary order parameter (POP) obtained from a magnetic multipolar analysis. The large t(2g) bandwidth renormalizes the strength of SOC and the Ir intersite exchange interaction dominates resulting in long-range magnetic order in the AP phase. In addition to SOC and Hubbard U, strong intradimer coupling is found to be crucial for the realization of the insulating state. At high pressure (HP) the system undergoes a structural transformation to the disordered cubic phase. In sharp contrast to the AP phase, the calculated exchange interactions in the HP phase are found to be much weaker and SOC dominates leading to a quantum spin-orbital liquid (SOL) state.
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| 3. |
- Nag, Abhishek, et al.
(författare)
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Origin of the Spin-Orbital Liquid State in a Nearly J=0 Iridate Ba3ZnIr2O9
- 2016
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 116:9
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Tidskriftsartikel (refereegranskat)abstract
- We show using detailed magnetic and thermodynamic studies and theoretical calculations that the ground state of Ba3ZnIr2O9 is a realization of a novel spin-orbital liquid state. Our results reveal that Ba3ZnIr2O9 with Ir5+ (5d(4)) ions and strong spin-orbit coupling (SOC) arrives very close to the elusive J = 0 state but each Ir ion still possesses a weak moment. Ab initio density functional calculations indicate that this moment is developed due to superexchange, mediated by a strong intradimer hopping mechanism. While the Ir spins within the structural Ir2O9 dimer are expected to form a spin-orbit singlet state (SOS) with no resultant moment, substantial frustration arising from interdimer exchange interactions induce quantum fluctuations in these possible SOS states favoring a spin-orbital liquid phase down to at least 100 mK.
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| 4. |
- Panda, S. K., et al.
(författare)
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Effect of spin orbit coupling and Hubbard U on the electronic structure of IrO2
- 2014
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 89:15, s. 155102-
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Tidskriftsartikel (refereegranskat)abstract
- We have studied in detail the electronic structure of IrO2 including spin orbit coupling (SOC) and electronelectron interaction, both within the generalized gradient approximation plus Hubbard U (GGA+ U) and GGA plus dynamical mean field theory (GGA+ DMFT) approximations. Our calculations reveal that the Ir t(2g) states at the Fermi level largely retain the J(eff) = 1/2 character, suggesting that this complex spin orbit entangled state may be robust even in metallic IrO2. We have calculated the phase diagram for the ground state of IrO2 as a function of U and find a metal insulator transition that coincides with a magnetic phase change, where the effect of SOC is only to reduce the critical values of U necessary for the transition. We also find that dynamic correlations, as given by the GGA+ DMFT calculations, tend to suppress the spin- splitting, yielding a Pauli paramagnetic metal for moderate values of the Hubbard U. Our calculated optical spectra and photoemission spectra including SOC are in good agreement with experiment, demonstrating the importance of SOC in IrO2.
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