اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدTwo-stage three-channel Kondo physics for an FePc molecule on the Au(111) surface
147
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We study an impurity Anderson model to describe an iron phthalocyanine (FePc) molecule on Au(111), motivated by previous results of scanning tunneling spectroscopy (STS) and theoretical studies. The model hybridizes a spin doublet consisting in one hole at the $3d_{z^2}$ orbital of iron and two degenerate doublets corresponding to one hole either in the $3d_{xz}$ or in the $3d_{yz}$ orbital (called $pi$ orbitals) with two degenerate Hund-rule triplets with one hole in the $3d_{z}$ orbital and another one in a $pi$ orbital. We solve the model using a slave-boson mean-field approximation (SBMFA). For reasonable parameters we can describe very well the observed STS spectrum between sample bias -60 mV to 20 mV. For these parameters the Kondo stage takes place in two stages, with different energy scales $T_K^z > T_K^pi$ corresponding to the Kondo temperatures related with the hopping of the $z^2$ and $pi$ orbitals respectively. There is a strong interference between the different channels and the Kondo temperatures, particularly the lowest one is strongly reduced compared with the value in the absence of the competing channel.
قيم البحث
اقرأ أيضاً
Adding a second Kondo channel to heavy fermion materials reveals new exotic symmetry breaking phases associated with the development of Kondo coherence. In this paper, we review two such phases, the hastatic order associated with non-Kramers doublet
ground states, where the two-channel nature of the Kondo coupling is guaranteed by virtual valence fluctuations to an excited Kramers doublet, and composite pair superconductivity, where the two channels differ by charge 2e and can be thought of as virtual valence fluctuations to a pseudo-isospin doublet. The similarities and differences between these two orders will be discussed, along with possible realizations in actinide and rare earth materials like URu2Si2 and NpPd5Al2.
We address the origin of the magnetic-field independent -|A| T^{1/2} term observed in the low-temperature resistivity of several As-based metallic systems of the PbFCl structure type. For the layered compound ZrAs_{1.58}Se_{0.39}, we show that vacanc
ies in the square nets of As give rise to the low-temperature transport anomaly over a wide temperature regime of almost two decades in temperature. This low-temperature behavior is in line with the non-magnetic version of the two-channel Kondo effect, whose origin we ascribe to a dynamic Jahn-Teller effect operating at the vacancy-carrying As layer with a C_4 symmetry. The pair-breaking nature of the dynamical defects in the square nets of As explains the low superconducting transition temperature T_{rm{c}}approx 0.14 K of ZrAs_{1.58}Se_{0.39}, as compared to the free-of-vacancies homologue ZrP_{1.54}S_{0.46} (T_{rm{c}}approx 3.7 K). Our findings should be relevant to a wide class of metals with disordered pnictogen layers.
We study theoretically and experimentally the infrared (IR) spectrum of an adamantane monolayer on a Au(111) surface. Using a new STM-based IR spectroscopy technique (IRSTM) we are able to measure both the nanoscale structure of an adamantane monolay
er on Au(111) as well as its infrared spectrum, while DFT-based ab initio calculations allow us to interpret the microscopic vibrational dynamics revealed by our measurements. We find that the IR spectrum of an adamantane monolayer on Au(111) is substantially modified with respect to the gas-phase IR spectrum. The first modification is caused by the adamantane--adamantane interaction due to monolayer packing and it reduces the IR intensity of the 2912 cm$^{-1}$ peak (gas phase) by a factor of 3.5. The second modification originates from the adamantane--gold interaction and it increases the IR intensity of the 2938 cm$^{-1}$ peak (gas phase) by a factor of 2.6, and reduces its frequency by 276 cm$^{-1}$. We expect that the techniques described here can be used for an independent estimate of substrate effects and intermolecular interactions in other diamondoid molecules, and for other metallic substrates.
This paper studies the two-channel Kondo lattice in the large-N limit at half-filling. In this model, the continuous channel-symmetry is spontaneously broken, forming a channel ferromagnet in which one conduction channel forms a Kondo insulator, whil
e the other remains conducting. The paper discusses how this ground-state can be understood using the concept of order fractionalization, in which the channel magnetization breaks up into an emergent spinor order parameter. By integrating out the fermions we derive an effective action that describes this symmetry breaking and its emergent collective modes. A remarkable observation is that topological defects in the order parameter carry a U(1) flux, manifested in the Aharonov-Bohm phase picked by electrons that orbit the defect. By studying the effective action, we argue that the phase diagram contains a non-magnetic transition between a large and a small Fermi surface.
For a mobile spin-1/2 impurity, coupled antiferromagnetically to a one-dimensional gas of fermions, perturbative ideas have been used to argue in favor of two-channel Kondo behavior of the impurity spin. Here we combine general considerations and ext
ensive numerical simulations to show that the problem displays a novel quantum phase transition between two-channel and one-channel Kondo screening upon increasing the Kondo coupling. We construct a ground-state phase diagram and discuss the various non-trivial crossovers as well as possible experimental realizations.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
