Khác biệt giữa bản sửa đổi của “Vật lý vật chất ngưng tụ”
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Năm 2009, David Field và đồng nghiệp tại Đại học Aarhus khám phá ra điện trường tự phát khi rạo ra các lớp mỏng của nhiều khí khác nhau. Khám phá này đưa đến sự mở rộng nghiên cứu của lĩnh vực spontelectrics.<ref>{{cite journal|last=Field|first=David|coauthors=Plekan, O.; Cassidy, A.; Balog, R.; Jones, N.C. and Dunger, J. |title=Spontaneous electric fields in solid films: spontelectrics|journal=Int.Rev.Phys.Chem.|date=12 Mar 2013|year=2013|doi=10.1080/0144235X.2013.767109|volume=32|issue=3|pages=345}}</ref>
==Lý thuyết==
Theoretical condensed matter physics involves the use of theoretical models to understand properties of states of matter. These include models to study the electronic properties of solids, such as the [[Drude model]], the [[Band structure]] and the [[density functional theory]]. Theoretical models have also been developed to study the physics of [[phase transition]]s, such as the [[Ginzburg–Landau theory]], [[critical exponent]]s and the use of mathematical techniques of [[quantum field theory]] and the [[renormalization group]]. Modern theoretical studies involve the use of [[numerical computation]] of electronic structure and mathematical tools to understand phenomena such as [[high-temperature superconductivity]], [[topological phase]]s and [[gauge symmetry|gauge symmetries]].
===Emergence===
{{main|Emergence}}
Theoretical understanding of condensed matter physics is closely related to the notion of [[emergence]], wherein complex assemblies of particles behave in ways dramatically different from their individual constituents.<ref name=coleman>{{cite book|last=Coleman|first=Piers|title=Introduction to Many Body Physics|year=2011|publisher=Rutgers University|url=http://web.archive.org/web/20100119134915/http://www.physics.rutgers.edu/~coleman/mbody/pdf/bk.pdf}}</ref> For example, a range of phenomena related to [[high temperature superconductivity]] are not well understood, although the microscopic physics of individual electrons and lattices is well known.<ref name=nsf-emergence>{{cite web|title=Understanding Emergence|url=http://www.nsf.gov/news/overviews/physics/physics_q01.jsp|publisher=National Science Foundation|accessdate=30 March 2012}}</ref> Similarly, models of condensed matter systems have been studied where [[collective excitation]]s behave like [[photon]]s and [[electron]]s, thereby describing [[electromagnetism]] as an emergent phenomenon.<ref name=levin-rmp>{{cite journal|last=Levin|first=Michael|coauthors=Wen, Xiao-Gang |title=Colloquium: Photons and electrons as emergent phenomena|journal=Reviews of Modern Physics|year=2005|volume=77|issue=3|doi=10.1103/RevModPhys.77.871|arxiv = cond-mat/0407140 |bibcode = 2005RvMP...77..871L|pages=871 }}</ref> Emergent properties can also occur at the interface between materials: one example is the [[Lanthanum aluminate-strontium titanate interface|lanthanum-aluminate-strontium-titanate interface]], where two non-magnetic insulators are joined to create conductivity, [[superconductivity]], and [[ferromagnetism]].
===Lý thuyết điện tử cho chất rắn===
{{main|Electronic band structure}}
The metallic state has historically been an important building block for studying properties of solids.<ref name=ashcroft/mermin>{{cite book|last=Ashcroft|first=Neil W.|last2=Mermin|first2=N. David|title=Solid state physics|year=1976|publisher=Harcourt College Publishers|isbn=978-0-03-049346-1}}</ref> The first theoretical description of metals was given by [[Paul Drude]] in 1900 with the [[Drude model]], which explained electrical and thermal properties by describing a metal as an [[ideal gas]] of then-newly discovered [[electron]]s. This classical model was then improved by [[Arnold Sommerfeld]] who incorporated the [[Fermi–Dirac statistics]] of electrons and was able to explain the anomalous behavior of the [[specific heat]] of metals in the [[Wiedemann–Franz law]].<ref name=ashcroft/mermin/> In 1913, X-ray diffraction experiments revealed that metals possess periodic lattice structure. Swiss physicist [[Felix Bloch]] provided a wave function solution to the [[Schrödinger equation]] with a [[Periodic function|periodic]] potential, called the [[Bloch wave]].<ref name=han-2010>{{cite book|last=Han|first=Jung Hoon|title=Solid State Physics|year=2010|publisher=Sung Kyun Kwan University|url=http://manybody.skku.edu/Lecture%20notes/Solid%20State%20Physics.pdf}}</ref>
Calculating electronic properties of metals by solving the many-body wavefunction is often computationally hard, and hence, approximation techniques are necessary to obtain meaningful predictions.<ref name=perdew-2010>{{cite journal|last=Perdew|first=John P.|coauthors=Ruzsinszky, Adrienn |title=Fourteen Easy Lessons in Density Functional Theory|journal=International Journal of Quantum Chemistry|year=2010|volume=110|pages=2801–2807|url=http://www.if.pwr.wroc.pl/~scharoch/Abinitio/14lessons.pdf|accessdate=13 May 2012|doi=10.1002/qua.22829|issue=15}}</ref> The [[Thomas–Fermi model|Thomas–Fermi theory]], developed in the 1920s, was used to estimate electronic energy levels by treating the local electron density as a [[Variational method|variational parameter]]. Later in the 1930s, [[Douglas Hartree]], [[Vladimir Fock]] and [[John C. Slater|John Slater]] developed the so-called [[Hartree–Fock method|Hartree–Fock wavefunction]] as an improvement over the Thomas–Fermi model. The Hartree–Fock method accounted for [[Exchange symmetry|exchange statistics]] of single particle electron wavefunctions, but not for their [[Coulomb interaction]]. Finally in 1964–65, [[Walter Kohn]], [[Pierre Hohenberg]] and [[Lu Jeu Sham]] proposed the [[density functional theory]] which gave realistic descriptions for bulk and surface properties of metals. The density functional theory (DFT) has been widely used since the 1970s for band structure calculations of variety of solids.<ref name=perdew-2010 />
===Phá vỡ đối xứng===
[[File:Melting icecubes.gif|thumb|upright|[[Ice]] melting into water. Liquid water has continuous [[translational symmetry]], which is broken in crystalline ice.]]
{{main|Symmetry breaking}}
Certain states of matter exhibit symmetry breaking, where the relevant laws of physics possess some [[Symmetry (physics)|symmetry]] that is broken. A common example is crystalline solids, which break continuous [[translational symmetry]]. Other examples include magnetized [[ferromagnetism|ferromagnets]], which break rotational symmetry, and more exotic states such as the ground state of a [[BCS theory|BCS]] [[superconductor]], that breaks [[U(1)]] rotational symmetry.<ref name=cnayak>{{cite book|last=Nayak|first=Chetan|title=Solid State Physics|publisher=UCLA|url=http://www.physics.ucla.edu/~nayak/solid_state.pdf}}</ref>
[[Goldstone's theorem]] in [[quantum field theory]] states that in a system with broken continuous symmetry, there may exist excitations with arbitrarily low energy, called the Goldstone [[boson]]s. For example, in crystalline solids, these correspond to [[phonon]]s, which are quantized versions of lattice vibrations.<ref name=goldstone>{{cite journal|last=Leutwyler|first=H.|title=Phonons as Goldstone bosons|journal=ArXiv|year=1996|arxiv=hep-ph/9609466v1.pdf|bibcode = 1996hep.ph....9466L|pages=9466 }}</ref>
===Sự chuyển pha===
{{main|Sự chuyển pha}}
The study of [[critical phenomena]] and [[phase transition]]s is an important part of modern condensed matter physics.<ref>{{cite book |title=Physics Through the 1990s|publisher=National Research Council|year=1986|chapter=Chapter 3: Phase Transitions and Critical Phenomena|url=http://books.google.com/books?id=bVq5_t9YwhYC&pg=PA7|isbn=0-309-03577-5}}</ref> Phase transition refers to the change of phase of a system, which is brought about by change in an external parameter such as [[temperature]]. In particular, [[quantum phase transition]]s refer to transitions where the temperature is set to zero, and the phases of the system refer to distinct [[ground state]]s of the [[Hamiltonian matrix|Hamiltonian]]. Systems undergoing phase transition display critical behavior, wherein several of their properties such as [[correlation length]], [[specific heat]] and [[Magnetic susceptibility|susceptibility]] diverge. Continuous phase transitions are described by the [[Ginzburg–Landau theory]], which works in the so-called [[mean field approximation]]. However, several important phase transitions, such as the [[Mott insulator]]–[[superfluid]] transition, are known that do not follow the Ginzburg–Landau paradigm.<ref name=balents-2005>{{cite journal|last=Balents|first=Leon|coauthors=Bartosch, Lorenz; Burkov, Anton; Sachdev, Subir and Sengupta, Krishnendu |title=Competing Orders and Non-Landau–Ginzburg–Wilson Criticality in (Bose) Mott Transitions|journal=Progress of Theoretical Physics|year=2005|volume=Supplement|issue=160|doi=10.1143/PTPS.160.314|arxiv = cond-mat/0504692 |bibcode = 2005PThPS.160..314B|pages=314 }}</ref> The study of phase transitions in strongly correlated systems is an active area of research.<ref name=Sachdev-LG-2010>{{cite journal|last=Sachdev|first=Subir|coauthors=Yin, Xi|title=Quantum phase transitions beyond the Landau–Ginzburg paradigm and supersymmetry|journal=Annals of Physics|year=2010|volume=325|issue=1|arxiv=0808.0191v2.pdf|doi=10.1016/j.aop.2009.08.003|pages=2|bibcode = 2010AnPhy.325....2S }}</ref>
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