Physics Letters B 759 (2016) 104–109
Contents lists available at ScienceDirect
Physics Letters B
www.elsevier.com/locate/physletb
Character of matter in holography: Spin–orbit interaction
Yunseok Seo
a
, Keun-Young Kim
b
, Kyung Kiu Kim
b,c
, Sang-Jin Sin
a,∗
a
Department of Physics, Hanyang University, Seoul 133-791, Republic of Korea
b
School of Physics and Chemistry, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
c
Department of Physics, College of Science, Yonsei University, Seoul 120-749, Republic of Korea
a r t i c l e i n f o a b s t r a c t
Article history:
Received
21 February 2016
Received
in revised form 13 May 2016
Accepted
20 May 2016
Available
online 25 May 2016
Editor:
M. Cveti
ˇ
c
Keywords:
Holography
Diamagnetism
DC
conductivity
Anomalous
Hall effect
Gauge/Gravity duality as a theory of matter needs a systematic way to characterise a system. We
suggest a ‘dimensional lifting’ of the least irrelevant interaction to the bulk theory. As an example, we
consider the spin–orbit interaction, which causes magneto-electric interaction term. We show that its
lifting is an axionic coupling. We present an exact and analytic solution describing diamagnetic response.
Experimental data on annealed graphite shows a remarkable similarity to our theoretical result. We also
find an analytic formulas of DC transport coefficients, according to which, the anomalous Hall coefficient
interpolates between the coherent metallic regime with ρ
2
xx
and incoherent metallic regime with ρ
xx
as we increase the disorder parameter β. The strength of the spin–orbit interaction also interpolates
between the two scaling regimes.
© 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP
3
.
Overview and summary: Recently, the gauge/gravity duality
[1–3] attracted much interests as a possible candidate for a reliable
method to calculate strongly correlated systems. It is a local field
theory in one higher dimensional space called “bulk”, with a few
classical fields coupled with anti-de Sitter (AdS) gravity. Since the
strong coupling in the boundary is dual to a weak coupling in the
bulk, the bulk fields can be considered as local order parameters
of a mean field theory in the bulk. It also provided a new mech-
anism
for instabilities in gravity language [4] which is relevant to
the superconductivity [5,6] and the metal insulator transition [7].
However, as a theory for materials, it is still in lack of one essen-
tial
ingredient, a way to distinguish one matter from the others.
Although electron–electron interaction is traded for the gravity in
the bulk, we still need to specify lattice–electron interactions to
characterise the system. Without it, we would not know what sys-
tem
we are working for.
Naively
one may try to introduce realistic lattice at the bound-
ary
to mimic the reality. However, its effects are mostly irrele-
vant
in the infrared (IR) limit. In strong coupling limit where no
quasiparticle exists, no Fermi surface (FS) exists either. Actually
in the absence of the FS, it is almost impossible to write down
any relevant interaction term in a local field theory in higher than
*
Corresponding author.
E-mail
addresses: yseo@hanyang.ac.kr (Y. Seo), fortoe@gist.ac.kr (K.-Y. Kim),
kimkyungkiu@gmail.com (K.K. Kim), sangjin.sin@gmail.com (S.-J. Sin).
1+1dimension.
1
Therefore non-local effect may be essential for
any interesting physics in strongly interacting system. One inter-
esting
aspect of a holographic theory is that any local interaction
in the bulk has non-local effect in the boundary [9]. Usually one
characterises a many body system in continuum limit by a few in-
teraction
terms rather than the detail of structure. Therefore, to
characterise a system in holographic theory, what we want to sug-
gest
is the dimensional-lifting, by which we mean promoting the
“system characterising interaction” of the boundary theory to a
term in the bulk theory using the covariant form of the interac-
tion.
One
may wonder what the gravity dual of the Maxwell the-
ory
is. In condensed matter, there are two components of elec-
tromagnetic
interaction. One is electron–electron interaction and
the other is lattice–electron interaction. While the main difficulty
is coming from the former, system is characterised by the lat-
ter.
Working hypothesis is that the electron–electron interaction
is taken care of by working in asymptotic AdS gravity. Our pur-
pose
is to include the electron–lattice interaction in this holo-
graphic
scheme, which is possible for two reasons. First, in any
boundary system with a conserved global U (1) charge, we have a
bulk Maxwell theory, which can accommodate usual electromag-
netic
field as a probe or an external source. It was used to build
1
See however ref. [8] for semi-holographic approach based on IR AdS2 and its
virtual CFT
2
, which is different from ours.
http://dx.doi.org/10.1016/j.physletb.2016.05.059
0370-2693/
© 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by
SCOAP
3
.