Ground-state phase diagram in the Kugel-Khomskii model with finite spin-orbit interactions

2018 ◽  
Vol 536 ◽  
pp. 369-371 ◽  
Author(s):  
Akihisa Koga ◽  
Shiryu Nakauchi ◽  
Joji Nasu
Keyword(s):  
Phase Diagram ◽  
Ground State ◽  
Spin Orbit ◽  
Ground State Phase Diagram ◽  
Spin Orbit Interactions

scholarly journals Wigner SU(4) symmetry, clustering, and the spectrum of $$^{12}$$C

2021 ◽  
Vol 57 (9) ◽  
Author(s):  
Shihang Shen ◽  
Timo A. Lähde ◽  
Dean Lee ◽  
Ulf-G. Meißner
Keyword(s):  
Excited States ◽  
Ground State ◽  
Nucleon Nucleon ◽  
Irreducible Representations ◽  
Spin Orbit ◽  
Hoyle State ◽  
Nucleon Interaction ◽  
Model Calculations ◽  
Nucleon Nucleon Interaction ◽  
Spin Orbit Interactions

AbstractWe present lattice calculations of the low-lying spectrum of $$^{12}$$ 12 C using a simple nucleon–nucleon interaction that is independent of spin and isospin and therefore invariant under Wigner’s SU(4) symmetry. We find strong signals for all excited states up to $$\sim 15$$ ∼ 15  MeV above the ground state, and explore the structure of each state using a large variety of $$\alpha $$ α cluster and harmonic oscillator trial states, projected onto given irreducible representations of the cubic group. We are able to verify earlier findings for the $$\alpha $$ α clustering in the Hoyle state and the second $$2^+$$ 2 + state of $$^{12}$$ 12 C. The success of these calculations to describe the full low-lying energy spectrum using spin-independent interactions suggest that either the spin-orbit interactions are somewhat weak in the $$^{12}$$ 12 C system, or the effects of $$\alpha $$ α clustering are diminishing their influence. This is in agreement with previous findings from ab initio shell model calculations.

scholarly journals Pressure Effects on the Magnetic Phase Diagram of the CeNMSb2 (NM: Au and Ag): A DFT Study

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2237
Author(s):  
Mowafaq Mohammad Alsardia ◽  
Jaekyung Jang ◽  
Joo Yull Rhee
Keyword(s):  
Ground State ◽  
Noble Metals ◽  
Easy Axis ◽  
Magnetic Phase ◽  
Magnetic Phase Diagram ◽  
Pressure Effects ◽  
Spin Orbit ◽  
Magnetic Ground State ◽  
Magnetic Easy Axis ◽  
Spin Orbit Interactions

We explore the influence of pressure on the magnetic ground state of the heavy-fermion antiferromagnet (ferromagnet) CeAuSb 2 (CeAgSb 2 ) using first-principles calculations. The total-energy differences obtained by including the spin-orbit interactions and the on-site Coulomb potential for the Ce-derived 4f-orbitals are necessary to realize the accurate magnetic ground state of CeNMSb 2 (NM: Au and Ag). According to our results, the appearance of a new magnetic phase of CeAuSb 2 (CeAgSb 2 ) at the pressure of 2.1 GPa (3.5 GPa) is due to the rotation of the magnetic easy axis from the <001> to the <100> direction. Additionally, our data confirm that CeAgSb 2 is antiferromagnetic (AFM) above a critical pressure P c , and such a tendency is expected for CeAuSb 2 and remains to be seen. Through the spin-orbit-coupling Hamiltonian and detailed information on the occupation of individual 4f-orbitals of the Ce atom obtained by the electronic-structure calculations, we can deduce the rotation of the magnetic easy axis upon the application of pressure. According to the present and previous studies, the differences among the magnetic properties of CeNMSb 2 (NM: Cu, Ag and Au) compounds are not due to the different noble metals, but due to the subtle differences in the relative position of Ce atoms and, in turn, different occupations of Ce 4f-orbitals.

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