Group leader:Yupeng WANG
Group members: Wuming LIU, Zhong FANG, Qingfeng SUN,
Biao WU, Junpeng CAO, Hanting WANG
Research field: Condensed Matter Theory
We have been working on the theoretical and computational studies for the unconventional superconductors, low-dimensional magnetism, quantum dots, transport, BEC, and some other strongly-correlated systems. There are totally 54 SCI papers were published, including 1 SCIENCE paper and 10 PRL papers.
2. List of significant publications or patents (less than 10)
[1] Z. Fang, and N. Nagaosa,
¡°Quantum versus Jahn-Teller Orbital Physics in YVO3 and LaVO3¡±,
Phys. Rev. Lett., (2004 accepted).
[2] B.Song and Yupeng Wang,
¡°Superconductivity of a hole-doped spin-orbital system¡±,
Phys. Rev. B 68, 104512(2003)
[3] Z. T. Jiang, Q. F. Sun, X. C. Xie, Y. P. Wang,
¡°Do Intradot Electron-Electron Interactions Induce Dephasing¡±
Phys. Rev. Lett. 93, 76802 (2004).
[4] R. Mathieu, A. Asamitsu, H. Yamada, K. S. Takahashi, M. Kawasaki,
Z. Fang, N. Nagaosa, and Y. Tokura,
¡°Scaling of the Anomalous Hall Effect in Sr1-xCaxRuO3¡±,
Phys. Rev. Lett., 93, 016602 (2004).
[5]Z. Fang, K. Takhashi, A. Asamitsu, T. Ogasawara, M. Kawasaki,
N. Nagaosa, Y. Tokura, K. Terakurae,
¡°Anomalous Hall Effect and Magnetic Monopoles in Momentum Space¡±,
SCIENCE, 302, 92 (2003).
[6]J. H. Jung, Z. Fang, J. P. He, and et al.,
¡°Change of electronic structure in Ca2RuO4 induced by orbital ordering¡±,
Phys. Rev. Lett. 91, 56403 (2003).
[7]Y. Motome, H. Seo, Z. Fang, N. Nagaosa,
¡°One-dimensional Confinement with Enhanced Instability to
Jahn-Teller Distortion in LaVO3¡±,
Phys. Rev. Lett. 90, 146602 (2003).
[8]Qing-feng Sun, Hong Guo, and Jian Wang
¡°A spin cell for spin current¡±,
Phys. Rev. Lett. 90,258301 (2003).
[9]Ping Zhang, Qi-Kun Xue, Yu-Peng Wang and Xin-Cheng
Xie
¡°Spin-Dependent Transport Through an Interacting Quantum
Dot¡±,
Phys. Rev. Lett. 89,286803 (2002).
[10]W.M. Liu, W.B. Fan, W.M. Zheng, J.Q. Liang, and
S.T. Chui,
¡°Quantum tunneling of Bose-Einstein condesates in optical
lattices under gravity¡±,
Phys. Rev. Lett. 88,
170408 (2002).
Proposer: Yupeng WANG
Members: Yupeng Wang£¬Qing-Feng Sun,Han-Ting Wang,Junpeng Cao, Shu Chen
Research Field: Theoretical study on the low-dimensional condensed matter systems
With the fast development of material science, more and more low-dimensional materials have been composed in the current years. In addition, the micro-fabrication techniques and laser-cooling and magnetic trap techniques provide powerful methods to prepare artificial low-dimensional systems in laboratory, such as quantum dots, quantum wires and cooling atoms in optical lattices etc. In these systems, because of the confined dimension, the quantum fluctuations and correlation effects play crucial roles. As well known, correlation effect, quantum fluctuation and quantum coherence are some basic problems in condensed matter physics, which are very important for us to understand these physical systems. On the other hand, study on these systems may lead us to find new quantum phenomena. Typical examples are high Tc superconductivity, quantum Hall effect and CMR.
We shall conduct theoretical research on the following directions:
We shall study the electronic structures, spin structures and transport properties of periodically arrayed quantum dot systems. Since in experiments such systems have become available and even controllable, we may predict and design functions of these materials. We shall study the quantum dot systems coupled with multi-band leads, such as quantum wires, which are the experimentally controllable multi-channel Kondo systems.
In conventional condensed materials, high-spin fermion system is rare. However, it can be realized conveniently in the cooling atom systems. An interesting problem is to study its condensation behavior. As well know, in BCS systems the basic objects are Cooper pairs. A direct question is that what is the basic objects in the high-spin condensates and how they condense?
Many low-dimensional spin systems have complex quantum phases, topological excitations. Recent researches also predicted that twisted boundaries may induce pure spin current in a spin chain. We shall study these problems and other physical problems related to quantum computation and quantum communication.
Propose some designations to the periodically arrayed quantum dot systems on substrates; clarify the transport mechanism of a quantum dot coupled to multi-band leads, develop the BCS-like theory of high spin fermion condensates in optical lattices; get deep insights to the spiral spinons, entanglement and spin current in low-dimensional spin systems.
All members of this group have pretty good research experience on related directions. Here I list some typical related publications in the past three years.
Transport properties of quantum dot systems:
1. Do intradot electron-electron interactions induce dephasing?
Phys. Rev. Lett. 93, 076802 (2004).
2.Spin-dependent transport through an interacting quantum dot
Phys. Rev. Lett. 89, 286803 (2002).
3. Antiresonance scattering at defect levels in the quantum conductance of a one-dimensional
system
Phys. Rev. B 65, 193402 (2002)
High-spin fermion systems:
1. Superconductivity of a hole-doped spin-orbital system
Phys. Rev. B 68, 104512(2003)
Phys. Rev. B 69, 092402 (2004)
Low-dimensional spin systems£º
1. Exact solution of the XXZ spin chain with unparallel boundary fields
Nucl. Phys. B 663, [FS], 487(2003)
2. Phase diagram and magnetization plateaus in the SU(4) spin ladder with rung anisotropy
Phys. Rev. B 66, 134403(2002)
3. Boundary defects in integrable spin ladders
Phys. Rev. B 65, 193402(2002)
4. Kondo effect in a host with fractional statistics: Absence of Kondo logarithms
Phys. Rev. B 64,125113 (2001)
5. Exact Solution of a Heisenberg liquid model with long-range coupling
Phys. Rev. B 63, 143347(2001)
Funding: Hundred-Talent-Project of CAS, Cooperation funding for overseas scientists of CAS, 5 NSFC grants, Excellent innovative group grant of NSFC, Cooperation grant for overseas outstanding young scientists of NSFC.