Sudhakar Yarlagadda
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 T106 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