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SUMMARY:物性セミナー/物理学教室談話会/第15回 NITEP談話
会
DTSTART;VALUE=DATE-TIME:20210428T070000Z
DTEND;VALUE=DATE-TIME:20210428T083000Z
DTSTAMP;VALUE=DATE-TIME:20220522T104814Z
UID:indico-event-79@indico.nitep.osaka-cu.ac.jp
DESCRIPTION:講師：寺谷義道（大阪市立大学）\n日時：4月28
日(水) 16:00-17:30\nタイトル：Roles of three-body correlations on n
onlinear current and noise through multilevel Anderson impurity\n要旨：
We study Kondo effect occurring in quantum impurity systems such as magnet
ic dilute alloys\, quantum dots\, and ultra-cold atoms. It is a many body
phenomenon that is caused by interactions between localized spins and cond
uction electrons. In addition to the spin\, other degrees of freedom bring
an interesting variety to the Kondo effect. A carbon nanotube quantum dot
has four degenerate localized levels consisting of the spin and orbital d
egrees of freedom. The four levels give rise to the SU(4) Kondo effect. It
is observed by measurements of nonequilibrium current and noise[1] .\n I
n order to examine the nonlinear transport of an N-level Anderson impurity
models at low temperatures T and low-bias voltages eV\, Fermi-liquid theo
ry has been expanded to arbitrary cases of electron filling Nd both phenom
enologically[2\,3] and microscopically[4-6]. The theory shows that the tra
nsport coefficients up to order of (eV)³ are determined by Fermi-liquid p
arameters: phase shifts\, linear susceptibilities\, and nonlinear three-bo
dy susceptibilities. We calculate these parameters as functions of Nd for
N=4\, 6 and 8 using two methods: Wilson numerical renormalization group (N
RG) and 1/(N-1) expansion[7]. The latter one is a large N theory which is
exact in the limit of N → ∞.\n The NRG results show that the three-bo
dy correlations significantly contribute to the nonequilibrium transport c
oefficients as Nd deviates from particle-hole symmetric point. We find tha
t the correlations can be described by a single parameter in a wide range
of 1 ≤ Nd ≤ N-1 for strong interactions. Such behavior of the correlat
ions is experimentally observed[8]. Furthermore\, we compare the NRG resul
ts with those obtained by 1/(N-1) expansion and find that the three-body c
orrelations are suppressed already for N=8.\n[1] M. Ferrier\, T. Arakawa\,
T. Hata\, R. Fujiwara\, R. Delagrange\, R. Weil\, R. Deblock\, R. Sakano\
, A. Oguri\, and K. Kobayashi\, Nat. Phys. 12\, 230 (2016).\n[2] C. Mora\,
and et al\, Phys. Rev. B 92\, 075120 (2015).\n[3] M. Filippone\, and et a
l\, Phys. Rev. B 98\, 075404 (2018).\n[4] A. Oguri and A. C. Hewson\, Phys
. Rev. B 97\, 035435 (2018).\n[5] Y. Teratani\, R. Sakano\, and A. Oguri\,
Phys. Rev. Lett. 125\, 216801 (2020).\n[6] Y. Teratani\, R. Sakano\, T. H
ata\, T. Arakawa\, M. Ferrier\, K. Kobayashi\, and A. Oguri\, Phys. Rev. B
102\, 165106 (2020).\n[7] A. Oguri\, Phys. Rev. B 85\, 155404 (2012).\n[8
] T. Hata\, Y. Teratani\, T. Arakawa\, S. Lee\, M. Ferrier\, R. Deblock\,
R. Sakano\, A. Oguri\, and K. Kobayashi\, DOI: 10.21203/rs.3.rs-91730/v1.\
n\nZoomを用いた遠隔セミナー形式での開催です。\n興味
ある方は、矢野(hideo_at_sci.osaka-cu.ac.jp)まで連絡ください
。\n\nhttps://indico.nitep.osaka-cu.ac.jp/event/79/
LOCATION:
URL:https://indico.nitep.osaka-cu.ac.jp/event/79/
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