A scenario for the formation of symmetry protected non-Fermi-liquid (NFL) Kondo effect (KE) with ... more A scenario for the formation of symmetry protected non-Fermi-liquid (NFL) Kondo effect (KE) with spin variable enumerating Kondo channels is suggested and worked out. In doubly occupied symmetric triple quantum dot within parallel geometry, the NFL low-energy regime arises provided the device possesses both source-drain and left-right parity. Kondo screening follows a multistage renormalization group mechanism: reduction of the energy scale is accompanied by the change of the relevant symmetry group from SO(8) to SO(5). At low energy, three phases compete: 1) under-screening spin triplet (conventional) KE; 2) spin singlet potential scattering; 3) NFL phase where the roles of spin and orbital degrees of freedom are swapped.
A scenario for the formation of non-Fermi-liquid (NFL) Kondo effect (KE) with spin variable enume... more A scenario for the formation of non-Fermi-liquid (NFL) Kondo effect (KE) with spin variable enumerating Kondo channels is suggested and worked out. In doubly occupied symmetric triple quantum dot within parallel geometry, the NFL low-energy regime arises provided the device possesses both source-drain and left-right parity. Kondo screening follows a multistage renormalization group mechanism: reduction of the energy scale is accompanied by the change of the relevant symmetry group from SO(8) to SO(5). At low energy, three phases compete: 1) under-screening spin triplet (conventional) KE; 2) spin singlet potential scattering; 3) NFL phase where the roles of spin and orbital degrees of freedom are swapped.
Physica E: Low-dimensional Systems and Nanostructures, 2003
It is shown that the resonance tunneling through a complex quantum dot with even occupation revea... more It is shown that the resonance tunneling through a complex quantum dot with even occupation reveals the hidden dynamical SO(n) symmetry of this dot. This symmetry is manifested in unconventional mechanisms of Kondo resonance formation, where the gate voltage may tune the rank n gradually. In a specific case of triple quantum dot, the regimes with n=3,4,5,7 can be achieved.
Over-screened Kondo effect is feasible in carbon nanotube quantum dot junction hosting a spin $\t... more Over-screened Kondo effect is feasible in carbon nanotube quantum dot junction hosting a spin $\tfrac{1}{2}$ atom with single $s$-wave valence electron (e.g Au). The idea is to use the two valleys as two symmetry protected flavor quantum numbers $\xi={\bf K}, {\bf K}'$. Perturbative RG analysis exposes the finite weak-coupling two-channel fixed point, where the Kondo temperature is estimated to be around $0.5\div5$~K. Remarkably, occurrence of two different scaling regimes implies a non-monotonic dependence of the conductance as function of temperature.
In this Thesis we develop a novel direction in the theory of nano-objects, i.e., structures of na... more In this Thesis we develop a novel direction in the theory of nano-objects, i.e., structures of nanometer size in a tunnel contact with macroscopic electron reservoirs (metallic leads). In particular we elucidate the Kondo effect predicted in tunneling through triple quantum dots and sandwich-type molecules adsorbed on metallic substrate, which are referred to as trimers. The unusual dynamical symmetry of nano-objects is one of the most intriguing problems, which arise in the theory of these systems. We demonstrate that trimers possess dynamical symmetries whose realization in Kondo tunneling is experimentally tangible. Such experimental tuning of dynamical symmetries is not possible in conventional Kondo scattering. We develop the general approach to the problem of dynamical symmetries in Kondo tunneling through nano-objects and illustrate it by numerous examples of trimers in various configurations, in parallel, in series and in ring geometries.
ABSTRACT A theory of Kondo tunneling through molecules adsorbed on metallic substrate is construc... more ABSTRACT A theory of Kondo tunneling through molecules adsorbed on metallic substrate is constructed and the underlying physics is exposed. It is shown that in the case of weak chemisorption the sandwich-type molecules manifest a novel type of Kondo effect that has not been observed in magnetically doped bulk metals. The exchange Hamiltonian of these molecules unveils unusual dynamical SO(n) symmetries instead of conventional SU(2) symmetry. These symmetries can be experimentally realized and the specific value of n can be controlled by gate voltage.
The physics of Kondo effect and related phenomena in a triangular triple quantum dot (TTQD) is st... more The physics of Kondo effect and related phenomena in a triangular triple quantum dot (TTQD) is studied. A fascinating property of TTQD is the interplay between continuous SU(2) symmetry in spin space and discrete C3v symmetry in real space. We show that this interplay is manifested in strong oscillations of conductance as a function of magnetic flux through TTQD due
A scenario for the formation of symmetry protected non-Fermi-liquid (NFL) Kondo effect (KE) with ... more A scenario for the formation of symmetry protected non-Fermi-liquid (NFL) Kondo effect (KE) with spin variable enumerating Kondo channels is suggested and worked out. In doubly occupied symmetric triple quantum dot within parallel geometry, the NFL low-energy regime arises provided the device possesses both source-drain and left-right parity. Kondo screening follows a multistage renormalization group mechanism: reduction of the energy scale is accompanied by the change of the relevant symmetry group from SO(8) to SO(5). At low energy, three phases compete: 1) under-screening spin triplet (conventional) KE; 2) spin singlet potential scattering; 3) NFL phase where the roles of spin and orbital degrees of freedom are swapped.
A scenario for the formation of non-Fermi-liquid (NFL) Kondo effect (KE) with spin variable enume... more A scenario for the formation of non-Fermi-liquid (NFL) Kondo effect (KE) with spin variable enumerating Kondo channels is suggested and worked out. In doubly occupied symmetric triple quantum dot within parallel geometry, the NFL low-energy regime arises provided the device possesses both source-drain and left-right parity. Kondo screening follows a multistage renormalization group mechanism: reduction of the energy scale is accompanied by the change of the relevant symmetry group from SO(8) to SO(5). At low energy, three phases compete: 1) under-screening spin triplet (conventional) KE; 2) spin singlet potential scattering; 3) NFL phase where the roles of spin and orbital degrees of freedom are swapped.
Physica E: Low-dimensional Systems and Nanostructures, 2003
It is shown that the resonance tunneling through a complex quantum dot with even occupation revea... more It is shown that the resonance tunneling through a complex quantum dot with even occupation reveals the hidden dynamical SO(n) symmetry of this dot. This symmetry is manifested in unconventional mechanisms of Kondo resonance formation, where the gate voltage may tune the rank n gradually. In a specific case of triple quantum dot, the regimes with n=3,4,5,7 can be achieved.
Over-screened Kondo effect is feasible in carbon nanotube quantum dot junction hosting a spin $\t... more Over-screened Kondo effect is feasible in carbon nanotube quantum dot junction hosting a spin $\tfrac{1}{2}$ atom with single $s$-wave valence electron (e.g Au). The idea is to use the two valleys as two symmetry protected flavor quantum numbers $\xi={\bf K}, {\bf K}'$. Perturbative RG analysis exposes the finite weak-coupling two-channel fixed point, where the Kondo temperature is estimated to be around $0.5\div5$~K. Remarkably, occurrence of two different scaling regimes implies a non-monotonic dependence of the conductance as function of temperature.
In this Thesis we develop a novel direction in the theory of nano-objects, i.e., structures of na... more In this Thesis we develop a novel direction in the theory of nano-objects, i.e., structures of nanometer size in a tunnel contact with macroscopic electron reservoirs (metallic leads). In particular we elucidate the Kondo effect predicted in tunneling through triple quantum dots and sandwich-type molecules adsorbed on metallic substrate, which are referred to as trimers. The unusual dynamical symmetry of nano-objects is one of the most intriguing problems, which arise in the theory of these systems. We demonstrate that trimers possess dynamical symmetries whose realization in Kondo tunneling is experimentally tangible. Such experimental tuning of dynamical symmetries is not possible in conventional Kondo scattering. We develop the general approach to the problem of dynamical symmetries in Kondo tunneling through nano-objects and illustrate it by numerous examples of trimers in various configurations, in parallel, in series and in ring geometries.
ABSTRACT A theory of Kondo tunneling through molecules adsorbed on metallic substrate is construc... more ABSTRACT A theory of Kondo tunneling through molecules adsorbed on metallic substrate is constructed and the underlying physics is exposed. It is shown that in the case of weak chemisorption the sandwich-type molecules manifest a novel type of Kondo effect that has not been observed in magnetically doped bulk metals. The exchange Hamiltonian of these molecules unveils unusual dynamical SO(n) symmetries instead of conventional SU(2) symmetry. These symmetries can be experimentally realized and the specific value of n can be controlled by gate voltage.
The physics of Kondo effect and related phenomena in a triangular triple quantum dot (TTQD) is st... more The physics of Kondo effect and related phenomena in a triangular triple quantum dot (TTQD) is studied. A fascinating property of TTQD is the interplay between continuous SU(2) symmetry in spin space and discrete C3v symmetry in real space. We show that this interplay is manifested in strong oscillations of conductance as a function of magnetic flux through TTQD due
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Papers by T. Kuzmenko