© 2026 Aqora Quantum S.A.S.

Terms Privacy Legal Notice

arXiv:cond-mat/9603175 · Physical review. B, Condensed matter

Anderson impurity in a semiconductor

Clare C. Yu, M. Guerrero

Published Sep 15, 1996• 13 citations

Abstract

We study an Anderson impurity in a semiconducting host using the density matrix renormalization group technique. We use the U=0 one-dimensional Anderson Hamiltonian at half filling as the semiconducting host since it has a hybridization gap. By varying the hybridization of the host, we can control the size of the semiconducting gap \ensuremath{\Delta}. We consider chains with 25 sites and we place the Anderson impurity (with U\ensuremath{\gtrsim}0) in the middle of the chain. We dope the half-filled system with one hole and we find two regimes: when the hybridization of the impurity is small such that the energy \ensuremath{\Delta}E to add a hole to the impurity site is less than \ensuremath{\Delta}/2, the hole density and the spin are localized near the impurity. When the hybridization of the impurity is large (\ensuremath{\Delta}E\ensuremath{\gtrsim}\ensuremath{\Delta}/2), the hole and spin density are spread over the lattice. Additional holes avoid the impurity and are extended throughout the lattice. Away from half filling, the semiconductor with an impurity is analogous to a double well potential with a very high barrier. We also examine the chemical potential as a function of electron filling, and we find that the impurity introduces midgap states when the impurity hybridization is small. \textcopyright{} 1996 The American Physical Society.

DOI: 10.1103/physrevb.54.8556

Related papers

Anderson impurity in the one-dimensional Hubbard model for finite-size systems

S. Costamagna, C. J. Gazza, M. E. Torio +1 more

An Anderson impurity in a Hubbard model on chains with finite length is studied using the density-matrix renormalization-group (DMRG) technique. In the first place, we analyzed how the reduction of electron density from half filling to quarter filling affects the Kondo resonance in the limit of Hubbard repulsion $U=0$. In general, a weak dependence with the electron density was found for the local density of states (LDOS), at the impurity except when the impurity, at half filling, is close to a mixed-valence regime. Next, in the central part of this paper, we studied the effects of finite Hubbard interaction on the chain at quarter filling. Our main result is that this interaction drives the impurity into a more defined Kondo regime although accompanied in most cases by a reduction of the spectral weight of the impurity LDOS. Again, for the impurity in the mixed-valence regime, we observed an interesting nonmonotonic behavior. We also concluded that the conductance, computed for a small finite bias applied to the leads, follows the behavior of the impurity LDOS, as in the case of noninteracting chains. Finally, we analyzed how the Hubbard interaction and the finite chain length affect the spin compensation cloud both at zero and at finite temperature, in this case using quantum Monte Carlo techniques.

arXiv:cond-mat/0608725•Physical Review B•Nov 6, 2006•25 citations

Single magnetic impurity in a correlated electron system: Density-matrix renormalization group study

Satoshi Nishimoto, Peter Fulde

We study a magnetic impurity embedded in a correlated electron system using the density-matrix renormalization group method. The correlated electron system is described by the one-dimensional Hubbard model. At half filling, we confirm that the binding energy of the singlet bound state increases exponentially in the weak-coupling regime and decreases inversely proportional to the correlation in the strong-coupling regime. The spin-spin correlation shows an exponential decay with distance from the impurity site. The correlation length becomes smaller with increasing the correlation strength. We find discontinuous reduction of the binding energy and of spin-spin correlations with hole doping. The binding energy is reduced by hole doping; however, it remains of the same order of magnitude as for the half-filled case.

Physical Review B•Jul 18, 2007•3 citations

Magnetic impurity in correlated electrons system

Satoshi Nishimoto, Peter Fulde

We study a magnetic impurity embedded in a correlated electron system using the density-matrix renormalization group method. The correlated electron system is described by the one-dimensional Hubbard model. At half filling, we confirm that the binding energy of the singlet bound state increases exponentially in the weak-coupling regime and decreases inversely proportional to the correlation in the strong-coupling regime. The spin-spin correlation shows an exponential decay with distance from the impurity site. The correlation length becomes smaller with increasing the correlation strength. We find discontinuous reduction of the binding energy and of spin-spin correlations with hole doping. The binding energy is reduced by hole doping; however, it remains of the same order of magnitude as for the half-filled case.

arXiv:cond-mat/0703074•Mar 2, 2007•0 citations

Effect of dispersion in thefband of the one-dimensional Anderson lattice model

M. Guerrero, Hervé M. Carruzzo

We study the effect of a small dispersion in the f band on the elementary excitations of the one-dimensional Anderson lattice at half filling. We use the density-matrix renormalization-group technique to study the strong-coupling case (large Coulomb repulsion U) and an analytic renormalization-group calculation for weak coupling. When U=0, even a small dispersion in the f band can close the hybridization gap. In contrast, when U is large, the quasiparticle gap remains open and is almost independent of the dispersion in the f band. This means that for a given value of the dispersion, there is a metal-insulator transition for some value of the Coulomb repulsion U. The analytic calculation shows that the transition occurs at U=0. In contrast to the quasiparticle gap, the spin gap is strongly suppressed by the dispersion in the f band. This suppression is associated with the enhancement of antiferromagnetic correlations. \textcopyright{} 1996 The American Physical Society.

Physical review. B, Condensed matter•Dec 15, 1996•1 citation

Magnetic impurity in the one-dimensional Hubbard model

Andrei A. Zvyagin, P. Schlottmann

The Hubbard chain with a magnetic impurity of arbitrary spin $S$ is studied using the Bethe ansatz technique. We consider two kinds of impurities which interact with itinerant electrons on the neighboring lattice sites without destroying the integrability. The correlations in the host always induce valence fluctuations at the impurity site. For a repulsive Hubbard $U$, an impurity coupled via antiferromagnetic exchange to the host reveals magnetic properties similar to those of the ordinary Kondo effect. In contrast, a hybridization impurity (Anderson-like) embedded into the attractive Hubbard model gives rise to essentially different magnetic behavior. This difference is a consequence of the spin gap in the host.

Physical review. B, Condensed matter•Jul 1, 1997•38 citations

Quantum phase transition in a gapped Anderson model: A numerical renormalization group study

Cătălin Paşcu Moca, Adrian Roman

We use the numerical renormalization group method to investigate the spectral properties of a single-impurity Anderson model with a gap $\ensuremath{\delta}$ across the Fermi level in the conduction-electron spectrum. For any finite $\ensuremath{\delta}>0$, at half filling the ground state of the system is always a doublet. Away from half filling a quantum phase transition (QPT) occurs as function of the gap value $\ensuremath{\delta}$, and the system evolves from the strong-coupling (SC) Kondo-type state, corresponding to $\ensuremath{\delta}<{\ensuremath{\delta}}_{C}$ toward a localized moment (LM) regime for $\ensuremath{\delta}>{\ensuremath{\delta}}_{C}$. The opening of the gap leads to the formation of one (two) bound states when the system is in the SC (LM) regime. The evolution across the QPT of their positions and the corresponding weights together with the dynamic properties of the model are investigated.

arXiv:1006.4022•Physical Review B•Jun 9, 2010•14 citations

We study an Anderson impurity in a semiconducting host using the density matrix renormalization group technique. We use the U=0 one-dimensional Anderson Hamiltonian at half filling as the semiconducting host since it has a hybridization gap. By varying the hybridization of the host, we can control the size of the semiconducting gap \ensuremath{\Delta}. We consider chains with 25 sites and we place the Anderson impurity (with U\ensuremath{\gtrsim}0) in the middle of the chain. We dope the half-filled system with one hole and we find two regimes: when the hybridization of the impurity is small such that the energy \ensuremath{\Delta}E to add a hole to the impurity site is less than \ensuremath{\Delta}/2, the hole density and the spin are localized near the impurity. When the hybridization of the impurity is large (\ensuremath{\Delta}E\ensuremath{\gtrsim}\ensuremath{\Delta}/2), the hole and spin density are spread over the lattice. Additional holes avoid the impurity and are extended throughout the lattice. Away from half filling, the semiconductor with an impurity is analogous to a double well potential with a very high barrier. We also examine the chemical potential as a function of electron filling, and we find that the impurity introduces midgap states when the impurity hybridization is small. \textcopyright{} 1996 The American Physical Society.

An Anderson impurity in a Hubbard model on chains with finite length is studied using the density-matrix renormalization-group (DMRG) technique. In the first place, we analyzed how the reduction of electron density from half filling to quarter filling affects the Kondo resonance in the limit of Hubbard repulsion

U=0

. In general, a weak dependence with the electron density was found for the local density of states (LDOS), at the impurity except when the impurity, at half filling, is close to a mixed-valence regime. Next, in the central part of this paper, we studied the effects of finite Hubbard interaction on the chain at quarter filling. Our main result is that this interaction drives the impurity into a more defined Kondo regime although accompanied in most cases by a reduction of the spectral weight of the impurity LDOS. Again, for the impurity in the mixed-valence regime, we observed an interesting nonmonotonic behavior. We also concluded that the conductance, computed for a small finite bias applied to the leads, follows the behavior of the impurity LDOS, as in the case of noninteracting chains. Finally, we analyzed how the Hubbard interaction and the finite chain length affect the spin compensation cloud both at zero and at finite temperature, in this case using quantum Monte Carlo techniques.

We study a magnetic impurity embedded in a correlated electron system using the density-matrix renormalization group method. The correlated electron system is described by the one-dimensional Hubbard model. At half filling, we confirm that the binding energy of the singlet bound state increases exponentially in the weak-coupling regime and decreases inversely proportional to the correlation in the strong-coupling regime. The spin-spin correlation shows an exponential decay with distance from the impurity site. The correlation length becomes smaller with increasing the correlation strength. We find discontinuous reduction of the binding energy and of spin-spin correlations with hole doping. The binding energy is reduced by hole doping; however, it remains of the same order of magnitude as for the half-filled case.

We study a magnetic impurity embedded in a correlated electron system using the density-matrix renormalization group method. The correlated electron system is described by the one-dimensional Hubbard model. At half filling, we confirm that the binding energy of the singlet bound state increases exponentially in the weak-coupling regime and decreases inversely proportional to the correlation in the strong-coupling regime. The spin-spin correlation shows an exponential decay with distance from the impurity site. The correlation length becomes smaller with increasing the correlation strength. We find discontinuous reduction of the binding energy and of spin-spin correlations with hole doping. The binding energy is reduced by hole doping; however, it remains of the same order of magnitude as for the half-filled case.

We study the effect of a small dispersion in the f band on the elementary excitations of the one-dimensional Anderson lattice at half filling. We use the density-matrix renormalization-group technique to study the strong-coupling case (large Coulomb repulsion U) and an analytic renormalization-group calculation for weak coupling. When U=0, even a small dispersion in the f band can close the hybridization gap. In contrast, when U is large, the quasiparticle gap remains open and is almost independent of the dispersion in the f band. This means that for a given value of the dispersion, there is a metal-insulator transition for some value of the Coulomb repulsion U. The analytic calculation shows that the transition occurs at U=0. In contrast to the quasiparticle gap, the spin gap is strongly suppressed by the dispersion in the f band. This suppression is associated with the enhancement of antiferromagnetic correlations. \textcopyright{} 1996 The American Physical Society.

The Hubbard chain with a magnetic impurity of arbitrary spin

S

is studied using the Bethe ansatz technique. We consider two kinds of impurities which interact with itinerant electrons on the neighboring lattice sites without destroying the integrability. The correlations in the host always induce valence fluctuations at the impurity site. For a repulsive Hubbard

U

, an impurity coupled via antiferromagnetic exchange to the host reveals magnetic properties similar to those of the ordinary Kondo effect. In contrast, a hybridization impurity (Anderson-like) embedded into the attractive Hubbard model gives rise to essentially different magnetic behavior. This difference is a consequence of the spin gap in the host.

We use the numerical renormalization group method to investigate the spectral properties of a single-impurity Anderson model with a gap $\ensuremath{\delta}$ across the Fermi level in the conduction-electron spectrum. For any finite $\ensuremath{\delta}>0$, at half filling the ground state of the system is always a doublet. Away from half filling a quantum phase transition (QPT) occurs as function of the gap value $\ensuremath{\delta}$, and the system evolves from the strong-coupling (SC) Kondo-type state, corresponding to $\ensuremath{\delta}<{\ensuremath{\delta}}_{C}$ toward a localized moment (LM) regime for $\ensuremath{\delta}>{\ensuremath{\delta}}_{C}$. The opening of the gap leads to the formation of one (two) bound states when the system is in the SC (LM) regime. The evolution across the QPT of their positions and the corresponding weights together with the dynamic properties of the model are investigated.