Delia Guerra - Academia.edu (original) (raw)
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Papers by Delia Guerra
The European Physical Journal Plus
We use exact diagonalization results to investigate how the ground state of a two-site, two-orbit... more We use exact diagonalization results to investigate how the ground state of a two-site, two-orbital Hubbard model evolves in terms of the crystal field energy and a magnetic spin symmetry breaking field. We show that, based on the behavior of a properly defined composite spin-orbital correlation function, the different regions of the related phase diagrams can be classified according to the extent to which spin and orbital degrees of freedom turn out to be correlated.
Physica B: Condensed Matter, 2018
Acta Physica Polonica A, 2018
We analyze the effects of a large spin-orbit coupling on the magnetic state of a d 1 transition-m... more We analyze the effects of a large spin-orbit coupling on the magnetic state of a d 1 transition-metal ion located in a tetrahedral environment. While in the ideal tetrahedral symmetry the spin-orbit coupling acts only as a perturbation on the atomic energy levels set by the crystal-field splitting, we demonstrate that its effects are strongly enhanced in the case of distorted geometries. In particular, we consider the specific case in which the tetrahedron is compressed along the z direction, and show that, by increasing the degree of flattening, a large spin-orbit interaction (i) can induce a substantial anisotropic, unquenched orbital momentum and (ii) can affect the hierarchy of the lowest energy levels that are involved in the magnetic exchange.
Transition Metal Oxides (TMOs) show a wealth of intriguing properties which are governed by the i... more Transition Metal Oxides (TMOs) show a wealth of intriguing properties which are governed by the interplay of charge, spin, and orbital degrees of freedom. Moreover, the comprehension of the features of strongly correlated TMOs with signi cant Spin Orbit Coupling (SOC) represents a challenging work and the interplay between large SOC and lattice geometry is undoubtedly a relevant ingredient in the exploration of such features. The most dramatic example of that occurs in iridates, where SOC deeply impacts the magnetic state, changing the character of the multiplet state within the t2g manifold in the case of an octahedral arrangement of the ions. Corresponding e ects in eg manifold have rarely been considered, due to the conventional wisdom that eg subshells ensure a perfectly quenched orbital momentum. In the rst part of the thesis, we study the in uence of SOC on the magnetic state of a d TM ion located in a tetrahedral environment, proving that its e ect can be strongly enhanced in...
The European Physical Journal Plus
We use exact diagonalization results to investigate how the ground state of a two-site, two-orbit... more We use exact diagonalization results to investigate how the ground state of a two-site, two-orbital Hubbard model evolves in terms of the crystal field energy and a magnetic spin symmetry breaking field. We show that, based on the behavior of a properly defined composite spin-orbital correlation function, the different regions of the related phase diagrams can be classified according to the extent to which spin and orbital degrees of freedom turn out to be correlated.
Physica B: Condensed Matter, 2018
Acta Physica Polonica A, 2018
We analyze the effects of a large spin-orbit coupling on the magnetic state of a d 1 transition-m... more We analyze the effects of a large spin-orbit coupling on the magnetic state of a d 1 transition-metal ion located in a tetrahedral environment. While in the ideal tetrahedral symmetry the spin-orbit coupling acts only as a perturbation on the atomic energy levels set by the crystal-field splitting, we demonstrate that its effects are strongly enhanced in the case of distorted geometries. In particular, we consider the specific case in which the tetrahedron is compressed along the z direction, and show that, by increasing the degree of flattening, a large spin-orbit interaction (i) can induce a substantial anisotropic, unquenched orbital momentum and (ii) can affect the hierarchy of the lowest energy levels that are involved in the magnetic exchange.
Transition Metal Oxides (TMOs) show a wealth of intriguing properties which are governed by the i... more Transition Metal Oxides (TMOs) show a wealth of intriguing properties which are governed by the interplay of charge, spin, and orbital degrees of freedom. Moreover, the comprehension of the features of strongly correlated TMOs with signi cant Spin Orbit Coupling (SOC) represents a challenging work and the interplay between large SOC and lattice geometry is undoubtedly a relevant ingredient in the exploration of such features. The most dramatic example of that occurs in iridates, where SOC deeply impacts the magnetic state, changing the character of the multiplet state within the t2g manifold in the case of an octahedral arrangement of the ions. Corresponding e ects in eg manifold have rarely been considered, due to the conventional wisdom that eg subshells ensure a perfectly quenched orbital momentum. In the rst part of the thesis, we study the in uence of SOC on the magnetic state of a d TM ion located in a tetrahedral environment, proving that its e ect can be strongly enhanced in...