The mission of XSG group is to study the structural, electronic, and magnetic properties of condensed matter systems at extreme conditions using novel synchrotron Xray techniques, assisted with transport, optical, and theoretical approaches. Particular interest is placed on electronic and magnetic structure and phase behavior, as well as electronic excitations in electron stronglycorrelated systems (such as high-Tc superconductors, CMR, Mott-insulators, spinorbit coupled correlated iridates) at high pressure.
Project one: High-pressure effects on superconductivity in cuprates
Motivation: since it was discovered nearly 30 years ago, high pressure superconductivity (HTSC)in cuprates has been studied mainly by doping method. However, pressure couldbecome another powerful tool to study the HTSC, since it can change the latticeparameter continuously without altering the chemistry of the system, which is incontrast to the doping method. Goal: to under the mechanism of HTSC through the study of thespin-fluctuation and stripe phase at high pressure, which are two crucialaspects for deciphering the mechanism of HTSC.
Project two: Study the pressured-induced novel quantum states in transition metal oxides
Motivation:the transition metal oxides (including 3d, 4d, and 5doxides), having comparable scales for their kinetic energy, Coulombinteraction, and spin-orbit coupling (in 5d oxides), provide an excellentplatform for studying new quantum states induced by pressure, such as spinliquid, topological insulator, Wely semi metal, confine metal, Mott transition,or even superconductivity. Goal:Searching for the novel quantum states and understand the underlyingmechanisms.
Project three: Pressures effects on the heavy-fermion systems
Motivation: During the pasttwo decades, considerable attention has been focused on heavy fermion (HF)systems, but high pressure study remains unexplored. Pressure could havesignificant impacts on both Kondo effects and RKKY interaction, which could induce novel emergent phenomena. Goal: we will focus on (1)Volume collapse of f electronmaterials; (2) Quantum criticality andquantum phase transition in heavy fermion systems; (3) Superconductivity.
Project four: Study thepressure effects on topological insulators
Motivation: topological Insulators, a new state ofquantum matter known as received a great attention owing to the presence ofgapless spin-filtered edge electronic states intheir surfaces, which permits the dissipation less transport of charge and spin.This is also a brand new field for high press scientists, which couldpotentially have new discoveries. Goal: Searching new quantum state andunderstand the underlying physics. New development: Compton Scattering;Quantum osillation.
Projectfive: study hdrides at high pressure
Rare-earthhydrides attract much attention recently due to (1) metal hydrides (MHx)provide a promising solution for a future hydrogen-based energy system (2) theydisplay very rich structural and electrical transitions as a function of the Hconcentration (that could be tuned by pressure). However, so far high-pressurestudy on these materials is still very limited to very low pressure regime.
Synchrotron facilities:
APS: https://www1.aps.anl.gov/
proposal submission: https://www1.aps.anl.gov/Users-Information/About-Proposals/Apply-for-Time
Spring-8: http://www.spring8.or.jp/en/
proposal submission: https://user.spring8.or.jp/apps/mypage/
ESRF: http://www.esrf.eu/
proposal submission: http://www.esrf.eu/UsersAndScience/UserGuide/Applying
NSLS-II: https://www.bnl.gov/ps/nsls2/about-NSLS-II.php
proposal submission: https://www.bnl.gov/ps/
PETRA-III: http://petra3.desy.de/index_eng.html
proposal submission: https://door.desy.de/door/
NSRRC_TPS: http://tpsportal.nsrrc.org.tw/
NSRRC_TLS: http://portal.nsrrc.org.tw/
Other links:
X-ray booklet : http://xdb.lbl.gov/
X-ray interaction with Matters: http://henke.lbl.gov/optical_constants/
XAS: http://xafs.org/defaultsite
pressure tools: http://kantor.50webs.com/ruby.htm