Sr. Prof. & Head Condensed Matter Physics (CMP) Division

Convener Faculty Search Committee

Jt. Coordinator of Colloquiums & Memorial Lectures

Coordinator of Joint International Phd Program

Saha Institute of Nuclear Physics (SINP)

Kolkata 700064

Email: y.sudhakar@saha.ac.in

Fax: 91-33-23374637

Off. Tel: 91-33-23370379 (ext. 2469)

Home Tel: 91-33-2359-2666

NEW "CAVENDISH-SINP" JOINT PHD PROGRAM:

Interested individuals with a strong CV can contact Prof. Y. Sudhakar

for a joint PhD program (in the area of condensed matter physics)

between SINP and Cavendish Lab (with PhD degree to be given

by Univ. of Cambridge). The joint PhD program is open only to

Saha Inst. students. The program was started by Prof. Peter

Littlewood, Prof. Y. Sudhakar, and Prof. M. K. Sanyal.

__Academics and Past
Experience:__

Bachelors: IIT Kanpur (CPI 9.3/10.0)

MS: Purdue Univ.

PhD in Condensed matter Physics - Purdue Univ. (GPA: 5.96/6.00)

Post Doctor at Max Planck Institute (Stuttgart)

Postdoc at NTT Basic Research labs (Japan)

Visiting Scientist at IMSc, Chennai

Asst. Prof. at IIT Delhi

Visiting Scientist at Texas Center for Superconductivity, Univ.
of Houston

Visiting Fellow at Cavendish Lab, Univ. of Cambridge

Visiting Scholar at Argonne National Lab, USA

Special
awards,
honors,
or
distinctions:

Fellowship at the Cavendish Lab (Univ. of Cambridge)

Our (Prof. B. Chakrabarti's and mine) joint proposal for Applied
Mathematics and Computational Science

Center at SINP was selected and funded, after screening at IMSc
(Chennai) and BARC (Mumbai) in 2004.

David Ross Fellowship at Purdue Univ.

Certificates of merit at IIT Kanpur

State Special Merit Scholarship for several years

National Science Talent Scholarship in Mathematics

Teaching
Experience:

Taught advanced courses in Condensed Matter Physics,

Many-body Physics, field theoretic methods in Condensed Matter Physics,

Magnetism, Fermi Liquid theory, etc. Also taught a course in Modern

Physics to undergraduates.

Interesting
Recent
Results
are here

Earlier
Reseach
Highlights:

We derived a quasiparticle pseudo Hamiltonian of an infinitesimally
polarized electron gas

which fully takes into account the many-body
effects of both charge and spin density

fluctuations. We calculated
self-consistently Fermi liquid parameters like the effective

mass, the effective g-factor, spin susceptibility in
two-dimensional
systems and found

reasonable agreement with experiments. My works on
electron gas [see especially PRB 38

10966 (1988); PRB 40
5432, (1990); PRB 49
7887 (1994);
PRB 49 14188
(1994)] are

well recognized and distinguished scientists (including Nobel
prize
winners) cite these works.

In fact G. F. Giuliani and G. Vignale have written a book
["Quantum Theory of the

Electron Liquid" (Cambridge)] in which
my work forms a major theme of the chapter

"The normal Fermi liquid" (Ch. 8).

I had included effects
of electron-impurity interactions [PRB 44
13101
(1991)] and showed that

the magnetization instability (at filling factor 2 in the quantum Hall
regime) predicted by Giuliani

and Quinnin [PRB 31
6228
(1985)]
does
occur;
the
experiment (measuring
diagonal resistivity

in GaInAs-InP heterostructures) I proposed was carried out by K.
von
Klitzing et al. [Phys. Rev.
B

47 4048
(1993)] and the
instability was explicitly demonstrated. The prediction was
also

verified by Mike Pepper et al. [PRL 79, 4449,
(1997)] through activation transport studies.

Several Nobel prize
winners (such as H. L. Stormer, D. C. Tsui, K. v. Klitzing,
and

H. Kroemer) and Buckley award winners (such as J. K. Jain, A. H.
MacDonald, and S. M. Girvin)

cite this work.

By using novel approaches, we (my student
Sanjoy Datta and I) solved
the

long-standing problem of analytically obtaining the Peierls instability
condition in

the Holstein model [Phys. Rev. B 75,
035124 (2007) and Phys. Rev. B 71, 235118 (2005)]

and predicted the phase diagram away from half-filling.

We (my student Sanjoy Datta and
I) derived an effective d-dimensional Hamiltonian

for a system of hard-core-bosons coupled to optical phonons in a
lattice. Away from half-filling,

we show that the presence of next-nearest-neighbor hopping in the
effective Hamiltonian leads

to a striking superfluid-to-supersolid transition [Solid State
Commun. **150** ,
2040 (2010)].

Some Recent Talks:

1) "Quantum phase transition and phase diagram at a general filling
in the

spinless one-dimensional Holstein model" at
the International seminar

and workshop - (April 10--May 11, 2007) on the "Strong
Correlations

and Angle-Resolved Photoemission Spectroscopy" at
MPI-Dresden, Germany.

2) "Cooperative Electron-phonon Interactions in One Dimension" at the

Moments and Multiplets in Mott Materials
program (Aug. 13--Dec. 14, 2007)

at KITP, Santa Barbara, USA.

3) "Cooperative Electron-phonon Interactions in One Dimension" at

Purdue Univ. (USA), Dec. 7 (2007).

4) "Cooperative Jahn-Teller effect in manganite chains", Oct. 22 (2007)
at

TCM group seminar, Cavendish lab, Univ. of Cambridge
(UK).

5) "Cooperative electron-phonon interactions in molecular chains"

at Imperial College (London, UK), Jan. 15 (2008).

6) "Cooperative Jahn-Teller effect in low-dimensional manganites"

at Univ. of Leicester (UK), Jan. 23 (2008).

7) "Cooperative electron-phonon interactions in molecular chains"

at Univ. of Bristol (UK) , Feb. 13 (2008).

8) "Magnetic-oxide nanoelectronics" at workshop on "Challenges

in nanoelectronics" at Saha Inst. on
Nov. 27 (2008).

9) "Quantum phase transition in an anisotropic
next-nearest-neighbor

Heisenberg model" at meeting on
"Entanglement in quantum condensed

matter systems" in IMSc (Chennai),
1-2 Dec. 2008.

10) "Quantum phase transition due to cooperative electron-phonon
interaction

in low-dimensional systems" at "Indian
condensed matter workshop"

organized by ICTS of TIFR, 9-22
Dec. (2008).

11) "Supersolidity in a Bose-Holstein model" at the

Low Dimensional
Electron Systems program (Jan. 20 -June 12, 2009)

at KITP, Santa Barbara, USA.

12) "Orbital ordering in undoped manganites via a generalized
Peierls instability'',

at the ICTS CONDENSED MATTER
PROGRAMME 2009, 5-22 Dec (2009).

13) "Supersolidity in a Bose-Holstein model" in the two-day
symposium during

A. J. Leggett’s visit to SINP (27-28
Jan./2010).

14) "Phase diagram of the one-dimensional Hubbard-Holstein model" at

"International Conference-cum-School on
Strongly Correlated and Disordered

Systems" held at IISc, Bangalore from Dec. 9 - 22,
2011.

15) "Study of maximal bipartite entanglement and robustness in

resonating-valence-bond states" at IMSC on
7/Dec./2011.

16) "Strong multiferroicity and giant magnetoelectric effect in

(Insulator)/(LaMnO3)n/(SrMnO3)n/(Insulator) heterostructure"

at the international conference on "Correlated
Oxides: novel

quantum states, device physics and energy
technologies"

March-April 2012, Cambridge Univ.

17) "Modeling multiferroicity in manganite heterostructures by

including cooperative
electron-phonon interaction" at the

discussion meeting, entitled "New
functionalities in electronic

and magnetic materials'', SSCU,
IISc, October 18-20, 2012.

18) "Polaron dynamics and decoherence in an interacting
two-spin

system coupled to optical phonon environment" at
the "Meeting on

quantum information processing and applications''
Harish-Chandra

Research Institute, Allahabad (India), Dec.
2-8, 2013.

19) "Polaron dynamics and decoherence in an interacting
two-spin

system coupled to optical phonon environment" at
I.I.T. Madras

on 30/Jan./2014.

20) "An analysis of the extremely anisotropic next-nearest-neighbour

Heisenberg Model" at IMSC (Chennai) on
4/Feb./2014.

21) Key-note talk on "Oxide devices -- the next revolution'' at the

National Seminar (2014) on ``Recent Advances in Physics''

at Berhampur Univ. jointly organized by Berhampur Univ. and IOP
(Bhubaneswar).

22) Colloquium on "Oxide electronics -- an answer to the
miniaturization challenge?"

at IISER Bhopal on 4/Sept./2015.

23) "Oxide double quantum dot: an answer to the qubit problem?"

at the "Meeting on quantum information processing and applications"

Harish-Chandra Research Institute, Allahabad (India); Dec. 7-13 (2015).

24) "Oxide double quantum dot – an answer to the qubit problem?"

Condensed Matter Seminar, Physics dept., Purdue; 19/Feb./2016

25) "Oxide systems – an answer to the qubit problem?"

Material Science Seminar, Argonne National Lab; 2/March/2016

26) "Oxide systems – an answer to the qubit problem?"

Condensed Matter Seminar, Physics dept.,
Univ. of Illinois at Urbana-Champaign 10/March/16

27) Plenary lecture on "Oxide devices – the best replacement for semiconductor devices?'' at the

International meeting on ``Highly Correlated
Systems-IMHCS-2017''

at Mahatma Gandhi Univ., Kerala, 24-26 March 2017.

Some Recent Publications:

"Correlation between battery material performance and cooperative electron-phonon interaction in $LiCo_yMn_{2-y}O_4$",

Krishna Rao Ragavendran, Prabhat Mandal, and Sudhakar Yarlagadda, Appl. Phys. Lett. 110, 143901 (2017).

"Checkerboard-supersolidity in a two-dimensional Bose–Holstein model"

Satyaki Kar and Sudhakar Yarlagadda, Annals of Physics 375, 322 (2016).

"Study of decoherence in models for hard-core bosons coupled to optical phonons",

A. Dey, M. Q. Lone, and S. Yarlagadda, Phys. Rev. B 92, 094302 (2015).

"Study of two-spin entanglement in singlet states",

M. Q. Lone, A. Dey, and S. Yarlagadda, Solid State Communications 202, 73 (2015).

"Polaron dynamics and decoherence in an interacting two-spin

system coupled to optical phonon environment"

Amit Dey and S. Yarlagadda, Phys. Rev. B 89, 064311 (2014).

"Analysis of the $t_2 - V$ model"

A. Ghosh and S. Yarlagadda, Phys. Rev. B 90, 045140 (2014).

"A study of cooperative breathing-mode in molecular chain",

Ravindra Pankaj and Sudhakar Yarlagadda, Phys. Rev. B 86, 035453 (2012).

"Decoherence free states in an infinite range Heisenberg model",

Muzaffar Q. Lone, Amit Dey, and Sudhakar Yarlagadda (arXiv:1205.4093).

"Strong multiferroicity and giant magnetoelectric effect in

$(Insulator)/(LaMnO_3)_n/(SrMnO_3)_n/(Insulator)$ heterostructure",

Sudhakar Yarlagadda, Peter B. Littlewood, Pinaki Majumdar, Ravindra Pankaj

(arXiv:1203.3283).

"Correlated singlet phase in the one-dimensional Hubbard-Holstein model",

Sahinur Reja, Sudhakar Yarlagadda, Peter B. Littlewood,

Phys. Rev. B 86, 045110 (2012).

"Phase diagram of one-dimensional Hubbard-Holstein model at
quarter-filling",

Sahinur Reja, Sudhakar Yarlagadda, Peter B. Littlewood,

Phys. Rev. B 84,
085127 (2011).

"Using many-body entanglement for coordinated action in game
theory problems",

Sudhakar Yarlagadda, Econophysics & Economics of
Games, Social Choices and

Quantitative Techniques (NEW ECONOMIC WINDOWS , Springer 2010).

"Supersolidity for hard-core-bosons coupled to optical
phonons",

Sanjoy Datta and Sudhakar Yarlagadda, Solid State
Communications **150** ,
2040 (2010).

"Orbital ordering in undoped manganites via a generalized
Peierls instability'',

S. Yarlagadda, P. B. Littlewood, M. Mitra, R. K. Monu,

Phys. Rev. B
80, 235123 (2009).

"Cooperative electron-phonon interaction in molecular chains",

Sudhakar Yarlagadda, arXiv:0712.0366

"Phase transition and phase diagram at a general
filling in
the spinless one-dimensional Holstein Model",

Sanjoy Datta and Sudhakar Yarlagadda, Phys. Rev. B 75,
035124 (2007).

''Many-Polaron Effects in the Holstein Model'',

Sanjoy Datta, Arnab Das, and Sudhakar
Yarlagadda, Phys. Rev. B, 71 235118 (2005).

''An analytic treatment of the Gibbs-Pareto behavior in
wealth distribution'',

Arnab Das and Sudhakar Yarlagadda,
Physica A, 353
529
(2005)

(cond-mat/0409329; old version
cond-mat/0310343).

" Jahn-Teller polarons and their superconductivity in a
molecular conductor",

R. Ramakumar and Sudhakar Yarlagadda, Phys.
Rev. B, 69
104519
(2004).

" Holstein polarons, Frohlich coupling and
superconductivity in a molecular conductor",

R. Ramakumar and Sudhakar Yarlagadda, Phys. Rev.
B, __67__ 214502 (2003).

"Analytic treatment of a trading market model", Arnab
Das and Sudhakar Yarlagadda,

Physica Scripta T__106__ 39 (2003).

" Microscopic approach to electron-phonon interaction physics
in half-doped manganites",

Sudhakar Yarlagadda, IJMPB __15__ No. 27,
3529 (2001).

"Mean-field approach to charge, orbital, and spin
ordering in manganites",

Sudhakar Yarlagadda and C. S. Ting, IJMPB __15__
2719
(2001).

"Colossal magnetoresistance using the small polaron
picture with finite band width effects",

Sudhakar Yarlagadda, Phys. Rev. B, __62__
14828
(2000).

"Mixed charge-spin response functions of an arbitrarily
polarized electron gas",

Sudhakar Yarlagadda, Solid State
Commun., __116__ 167 (2000).

Comment on "Spin dependent hopping and colossal
negative magnetoresistance in

epitaxial NdSrMnO3 films in fields upto 50T",

Sudhakar Yarlagadda, Phys. Rev. Lett., __84__
4017
(2000).

"Screened interaction and self-energy in an
infinitesimally polarized electron gas via

Kukkonen-Overhauser method",

Sudhakar Yarlagadda and G. F. Giuliani, Phys.
Rev. B, __61__ 12556 (2000).

Selected Earlier Publications:

``Towards a new picture of the fractional quantum Hall
effect'',

S. Yarlagadda, Physica B, 223-224, 640 (1996).

``Many-body local fields and Fermi liquid parameters in a
quasi-two-dimensional electron liquid'',

S. Yarlagadda and G. F. Giuliani, Phys. Rev. B. 49, 14188 (1994).

``Landau theory of the Fermi liquids and the

integration-over-the-coupling-constant algorithm'',

S. Yarlagadda and G. F. Giuliani, Phys. Rev. B. 49, 14172 (1994).

``Quasiparticle pseudo hamiltonian of an infinitesimally polarized
Fermi liquid'',

S. Yarlagadda and G. F. Giuliani, Phys. Rev. B. 49, 7887 (1994).

``Fermi liquid theory in the low density two-dimensional Hubbard
model'',

S. Yarlagadda and S. Kurihara, Phys. Rev. B. 48, 10 567 (1993).

``Negative thermodynamic density of states and charge density wave

instability in the lowest Landau level'',

S. Yarlagadda, Phys. Rev. B 48, 4707 (1993).

``Magnetization instabilities at tilted magnetic fields in the quantum
Hall regime'',

S. Yarlagadda, Phys. Rev. B 44, 13101 (1991).

``Nuclear spin relaxation due to a two-dimensional electron gas'',

S. Yarlagadda and R. R. Gerhardts,

Proceedings of the 20th International Conference on the Physics
of Semiconductors, Thessaloniki, Greece,

edited by E.M.
Anastassakis and J.D. Joannopoulos (World Scientific,
Singapore, 1990), p. 993.

``Many-body local fields and quasiparticle renormalization effects in
two dimensional electronic systems'',

S. Yarlagadda and G. F. Giuliani, Surface Science,

229, 410 (1990).

``Spin susceptibility in a two-dimensional electron gas'',

S. Yarlagadda and G. F. Giuliani, Phys. Rev. B 40, 5432 (1989).

``Exact asymptotic behavior of the charge and spin susceptibilities in
an interacting Fermi liquid'',

S. Yarlagadda and G. F. Giuliani, Phys. Rev. B 39, 3386 (1989).

``Quasiparticle energy and interaction in a normal electron
liquid'',

S. Yarlagadda and G. F. Giuliani, Solid State Commun. 69, 677 (1989).

``Many-body effective mass and anomalous g factor in
inversion layers'',

S. Yarlagadda and G. F. Giuliani, Phys. Rev. B 38, 10966 (1988).

__Books/Journals
written/edited:__

One of the editors of proceedings of the International
Conference on Strongly Correlated

Electron Systems (SCES-Y2k) published in IJMPB __15__
Nos.
19&20
(2001).

One of the editors of proceedings of the International
Workshop on Econophysics of

Wealth Distributions (Springer 2005).

__Current Research
Interests:__

Manganite physics (CMR, charge, orbital, and spin ordering,
etc.), Transition metal oxides in general,

Oxide heterostructures, Hubbard-Holstein model, Study of
coexisting long-range orders (e.g.,
superconductivity

and charge-density-wave), Molecular
superconductivity, Econophysics,
Quantum computation and

quantum
information, Many-body effects in electron gas,
Quantum Hall effect, Fermi
liquid theory,

and
Many-body physics in general.

__Collaborations:
__

Argonne National Lab:

Prof. Peter Littlewood

Purdue Univ.:

Prof. G.F. Giuliani

Prof. A. W. Overhauser

Texas Center for Superconductivity, Univ. of Houston:

Prof. C.S. Ting

Max Planck Inst., Stuttgart:

Prof. K. von Klitzing

IMSc, Chennai:

Prof. G. Baskaran

HRI, Allahabad:

Prof. P. Majumdar