凝聚态物理实验第八章

1、Final review of the courseThe original goals of this course:familiar with topics and techniques in modern CMPbasic understanding at the phenomenological levelappreciation of the colorfulness and wonderfulness of CMPfoster independent and critical thinking “Selected Topics in Experimental CMP”Outline

2、 of the courseChapter 1: Conventional metal physics: electrons and phononsChapter 2: Transport phenomenaChapter 3: Metal-insulator transitions: Mott, Anderson, PeierlsChapter 4: Surface and interfaceChapter 5: Low dimensional electron systems: 2D, 1D, 0DChapter 6:Magnetism and the Kondo effect Chapt

3、er 7: High temperature superconductivityChapter 1: brief review of electrons and phononsThe Drude model: free electron gas, classical statisticsThe Sommerfeld model: quantum version of the Drude model = free electron gas + Fermi distributionThe Landau Fermi Liquid theory: justified the FEG model, on

4、ly need quantitative modification, quasiparticles Band theory: Bloch theorem and the formation of band, origin and significance of band gapLattice vibrations: Harmonic oscillator modelDebye model: phonons as bosonic particlesChapter 2: transport phenomenaDefinition of transport: J = TFPure electrica

5、l and thermal transport: and The Boltzmann equationsThermoelectric transport and thermoelectric applications: ZTFormal transport equations:Transport in magnetic field Chapter 3: metal-insulator transitions (MIT)Mott insulator: MIT induced by strong Coulomb repulsion.The Hubbard model:,ijiii jiHtccUn

6、 n EF WU=0DOSEFUW UEFU/2EF+U/2DOSThe band structure of the Hubbard model (half-filled band):Chapter 3: metal-insulator transitions (MIT)Anderson localization: insulating states due to disorders.The Anderson Hamiltonian:The mobility edge:Weak localization:Alocalizedlocalizedextended-ccFphase coherent

7、 backscatteringChapter 3: metal-insulator transitions (MIT)Peierls transition: MIT due to electron-phonon coupling.Peierls Theorem:“a one-dimensional equally spaced chain with one electron per ion is unstable”.-kFkF=/2aa-2a-Chapter 4: surface and interfaceSurface reconstruction and surface electroni

8、c stuctureMBE, STM, ARPES, Quantum Well2m 2mPb quantum well on Si(111)Quantization and oscillation of the electronic structureChapter 5: low dimensional electron system2DEG: realization; conductivity and resistivity tensorQuantum Hall effect: quantized Hall plateau RH = h/ie2 and vanishing resistivi

9、ty. Origin of IQHE: Landau Levels; localized bulk states; 1D edge states; single-electron effect FQHE: modulation doping; fractional Hall plateau; composite fermion model; fractionally charged quasiparticle; many-body effect due to strong electron correlationGraphene: 2D Dirac fermion; anomalous QHE

10、; great potentials in applicationsChapter 5: low dimensional electron system1D electron system: non-Fermi liquid; Luttinger liquidLinear dispersion and bosonic excitationsSpin charge separation: spinons and holons0D electron system: quantum dotCoulomb blockade and single electron transistorsArtifici

11、al atoms Chapter 6: magnetism and the Kondo effectBasic magnetic phenomena: para; dia; ferro; antiferroMagnetic interactions: dipolar; exchange; superexchange; double exchange; RKKY Magnetic measurementsFrustrated magnet: spin iceGMR: spin-dependent band structure and spin-dependent transport; Motts

12、 two current modelCMR in manganitesChapter 6: magnetism and the Kondo effectThe Kondo effectResistivity minimumMagnetic impurity and Anderson modelKondos solution: second order spin-flip scattering involving the impurity spinKondo problemKondo screening cloud; Kondo temperature; Kondo resonanceKondo

13、 effect in low D systemsChapter 6: high TC superconductivityHistory of superconductivityCrystal structure of cuprates: the CuO2 planePairing symmetry: d-waveThe anomalous normal state: pseudogap phaseIt is still a well-defined big puzzle!Come to solve it!Lots of controversies in existing theories an

14、d experiments, so be careful!CMP for undergraduates: it is a perfect world!Perfect lattice infinite lattice weak interactions Development of CMPlow dimensionalityPWA localizationQuantum wellMottSCMagnetism, GMRFQHEQHELL, QDCMR el-el el-ph el-spinimpurityKondoHigh TCCDW Novel materials synthesis: Fin

15、ding new materials; accurate control of structure and composition Novel experimental techniques: STM; neutron scattering; ARPES; MBE; nanofabrication Extreme physical conditions: Ultra low T, super strong B, super high P, ultra high vacuum Driving forces for discoveries in CMP Be passionate: Enjoy it! Love it!Some suggestions and expectations Be bold: It is like an adventure, no guts, no glory! Be patient: Dont give up! Stay with the problem till its solved! Be persistent: Push it hard! Be the best in what you do! Ye Cun Zhou Xia