| 词条 | Samarium hexaboride |
| 释义 |
| ImageFile = CaHexaboride.png | ImageSize = | ImageAlt = | IUPACName = | OtherNames = | Section1 = {{Chembox Identifiers | CASNo = 12008-30-9 | PubChem = | SMILES = | Section2 = {{Chembox Properties | Sm=1|B=6 | Appearance = | Density = | MeltingPt = 2400 °C ±100[1] | BoilingPt = | Solubility = | Section3 = {{Chembox Hazards | MainHazards = | FlashPt = | AutoignitionPt = }} Samarium hexaboride (SmB6) is an intermediate-valence compound where samarium is present both as Sm2+ and Sm3+ ions at the ratio 3:7.[2] It belongs to a class of Kondo insulators. At temperatures above 50 K its properties are typical of a Kondo metal, with metallic electrical conductivity characterized by strong electron scattering, whereas at low temperatures, it behaves as a non-magnetic insulator with a narrow band gap of about 4–14 meV.[3] The cooling-induced metal-insulator transition in SmB6 is accompanied by a sharp increase in thermal conductivity, peaking at about 15 K. The reason for this increase is that electrons do not contribute to thermal conductivity at low temperatures, which is instead dominated by phonons. The decrease in electron concentration reduced the rate of electron-phonon scattering.[4] New research seems to show that it may be a topological insulator.[5][6][7] The increasing electrical resistance with a reduction in temperature indicates that the material behaves as an insulator; however, recent measurements reveal a Fermi surface (an abstract boundary of electrons in momentum space) characteristic of a good metal, indicating a more exotic dual metal-insulating ground state[8][9]. The electrical resistivity at temperatures below 4K displays a distinct plateau,[10] which is thought to be the coexistence of an insulating state (bulk) and a conducting state (surface). At temperatures approaching absolute zero, the quantum oscillations of the material grow as the temperature declines, a behavior that contradicts both the Fermi analysis and the rules that govern conventional metals.[8][11][9] While it has been argued that quantum oscillations on samples grown from aluminium flux[12] may arise from aluminum inclusions[13], such an explanation is excluded for samples grown by the image furnace method[8][10] rather than by the flux growth method[12][13]. See also
References1. ^Plenum Press Handbooks of High-Temperature Materials: No. 1 Materials Index p42 2. ^{{cite journal|last1=Nickerson|first1=J.|last2=White|first2=R.|last3=Lee|first3=K.|last4=Bachmann|first4=R.|last5=Geballe|first5=T.|last6=Hull|first6=G.|title=Physical Properties of SmB6|journal=Physical Review B|volume=3|pages=2030|year=1971|doi=10.1103/PhysRevB.3.2030|issue=6|bibcode = 1971PhRvB...3.2030N }} 3. ^{{cite journal|doi=10.1103/PhysRevB.52.R14308|last1=Nyhus|year=1995|first1=P.|pages=R14308|volume=52|last2=Cooper|journal=Physical Review B|first2=S.|last3=Fisk|first3=Z.|last4=Sarrao|first4=J.|title=Light scattering from gap excitations and bound states in SmB6|issue=20|bibcode = 1995PhRvB..5214308N }} 4. ^{{cite journal|last1=Sera|first1=M.|last2=Kobayashi|first2=S.|last3=Hiroi|first3=M.|last4=Kobayashi|first4=N.|last5=Kunii|first5=S.|title=Thermal conductivity of RB6 (R=Ce, Pr, Nd, Sm, Gd) single crystals|journal=Physical Review B|volume=54|pages=R5207|year=1996|doi=10.1103/PhysRevB.54.R5207|issue=8|bibcode = 1996PhRvB..54.5207S }} 5. ^{{cite journal |last=Botimer|arxiv=1211.6769 |first1=J. |author2=Kim |author3=Thomas |author4=Grant |author5=Fisk |author6=Jing Xia |title=Robust Surface Hall Effect and Nonlocal Transport in SmB6: Indication for an Ideal Topological Insulator |year=2013 |doi=10.1038/srep03150 |pmid=24193196 |pmc=3818682 |volume=3 |pages=3150 |journal=Scientific Reports|bibcode=2013NatSR...3E3150K }} 6. ^{{cite journal |last=Xiaohang Zhang|author2=N. P. Butch |author3=P. Syers |author4=S. Ziemak |author5=Richard L. Greene |author6=Johnpierre Paglione |title=Hybridization, Inter-Ion Correlation, and Surface States in the Kondo Insulator SmB6 |year=2013 |journal=Phys. Rev. X|volume=3|issue=1|pages=011011|doi=10.1103/PhysRevX.3.011011|arxiv=1211.5532|bibcode=2013PhRvX...3a1011Z}} 7. ^{{cite journal |last=Wolgast|arxiv=1211.5104 |author2=Cagliyan Kurdak |author3=Kai Sun |author4=Allen |author5=Dae-Jeong Kim |author6=Zachary Fisk |title=Discovery of the First Topological Kondo Insulator: Samarium Hexaboride |year=2012 |doi=10.1103/PhysRevB.88.180405 |volume=88 |issue=18 |pages=180405 |journal=Physical Review B|bibcode=2013PhRvB..88r0405W |url=http://www.escholarship.org/uc/item/4fj5s56d }} 8. ^1 2 {{cite journal|author1=B. S. Tan|author2=Y.-T. Hsu|author3=B. Zeng|author4=M. Ciomaga Hatnean|author5=N. Harrison|author6=Z. Zhu|author7=M. Hartstein|author8=M. Kiourlappou|author9=A. Srivastava|year=2015|title=Unconventional Fermi surface in an insulating state|journal=Science|volume=349|issue=6245|pages=287–290|arxiv=1507.01129|bibcode=2015Sci...349..287T|doi=10.1126/science.aaa7974|pmid=26138105|author10=M. D. Johannes|author11=T. P. Murphy|author12=J.-H. Park|author13=L. Balicas|author14=G. G. Lonzarich|author15=G. Balakrishnan|author16=Suchitra Sebastian}} 9. ^1 {{Cite news|url=https://www.quantamagazine.org/samarium-hexaboride-crystal-blurs-metal-insulator-line-20150702/|title=Samarium Hexaboride Crystal Blurs Metal-Insulator Line {{!}} Quanta Magazine|work=Quanta Magazine|access-date=2018-11-22}} 10. ^1 {{cite journal |author1=M. Ciomaga Hatnean |author2=M. R. Lees |author3=D. Mck. Paul |author4=G. Balakrishnan |title=Large, high quality single-crystals of the new Topological Kondo Insulator, SmB6 |journal=Nature |volume=3 |year=2013 |doi=10.1038/srep03071 |pmid=24166216 |pmc=3810659 |issue=3071|pages=3071 }} 11. ^{{Cite web|title = Puzzling material acts as conductor and insulator at the same time|first=Dario |last=Borghino |date=July 7, 2015|url = http://www.gizmag.com/samarium-hexaboride-conductor-insulator/38335/|website = www.gizmag.com|accessdate = 2015-07-08}} 12. ^1 {{Cite journal|last=Li|first=G.|last2=Xiang|first2=Z.|last3=Yu|first3=F.|last4=Asaba|first4=T.|last5=Lawson|first5=B.|last6=Cai|first6=P.|last7=Tinsman|first7=C.|last8=Berkley|first8=A.|last9=Wolgast|first9=S.|date=2014-12-05|title=Two-dimensional Fermi surfaces in Kondo insulator SmB6|url=http://science.sciencemag.org/content/346/6214/1208|journal=Science|language=en|volume=346|issue=6214|pages=1208–1212|doi=10.1126/science.1250366|issn=0036-8075|pmid=25477456}} 13. ^1 {{Cite arxiv |author1=S. M. Thomas |author2=Xiaxin Ding |author3=F. Ronning |author4=V. Zapf |author5=J. D. Thompson |author6=Z. Fisk |author7=J. Xia |author8=P. F. S. Rosa |title=Quantum oscillations in flux-grown SmB6 with embedded aluminum |eprint=1806.00117 |year=2018 }} 3 : Samarium compounds|Borides|Correlated electrons |
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