IJS KOLOKVIJ, 13.2.2008, prof. Mendels

Tue Feb 12 14:45:35 CET 2008

Vabim vas na 12. predavanje iz sklopa "Kolokviji na IJS" v letu 2007/08, ki bo v sredo, 13. februarja 2008, ob 13:00 uri v Veliki predavalnici Instituta >Jožef Stefan< na Jamovi cesti 39 v Ljubljani. Napovednik predavanja najdete tudi na naslovu http://www.ijs.si/ijsw/Koledar_prireditev, posnetke preteklih predavanj pa na http://videolectures.net/kolokviji_ijs. 

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Prof. Philippe Mendels

Nova eksotična stanja v frustriranih antiferomagnetih 

S pojmom frustracije in degeneracije se v najbolj čisti obliki srečamo v magnetizmu. Močno frustrirani magneti pogosto izkazujejo nova kvantna in klasična stanja kjer frustracija v magnetnih interakcijah in makroskopska degeneracija igrata ključno vlogo. To raziskovalno področje je neprestano rastlo v zadnjih dveh desetletjih, vse od P.W. Andersonovega predloga modela resonančnih valenčnih stanj v visokotemperaturnih superprevodnikih najprej osnovanega na modelu trikotnega frustriranega antiferomagneta. 

V prvem delu predavanja bomo vpeljal pojem frustriranih antiferomagnetov in nekatere pomembne parametre, ki določajo fundamentalno nova osnovna stanja, kot so spinski led, spinska tekočina ali druga podobna stanja. Pripravil bom tudi pregled ključnih eksperimentov in eksperimentalnih sistemov. 

V drugem delu predavanja pa se bom osredotočil na spinske tekočine in poudaril pomen dinamičnih in statičnih informacij, ki jih lahko razberemo iz lokalnih tehnik, kot sta jedrska magnetna resonanca in mionska spinska rotacija. 

V zadnjem delu pa bom opisal nedavno sintetizirani sistem Herbertsmithite, ZnCu3(OH)6Cl2, ki se je pojavil kot eden od najbližjih približkov kvantne spinske tekočine [Physics Today, February 2007].   

Predavanje bo v angleščini.

http://old-www.u-psud.fr/anglais.nsf/index.htm!OpenPageUniversity Paris-Sud 11 Orsay, France

Lepo vabljeni!

We would like to invite you to 12th lecture of the "Kolokvij na IJS" in the school year 2007/08. The lecture will be held on Wednesday, Feb 13 2008, at 1 pm at JSI main lecture hall, Jamova 39, Ljubljana. The abstract of the lecture can be found on website: http://www.ijs.si/ijsw/Koledar_prireditev, the previous recorded lectures can be found on website: http://videolectures.net/kolokviji_ijs. 

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Prof. Philippe Mendels

Novel States in Frustrated Antiferromagnets

Frustration and degeneracy are at the heart of much important science, from protein folding to emergent electromagnetism, but reach their purest manifestation in magnetic materials. Highly Frustrated Magnetism yields novel quantum and classical states where frustration of interactions and macroscopic degeneracy play a leading role. The field has been constantly growing for the past two decades after the seminal proposal of an interpretation of High Temperature Superconductivity in terms of a resonating valence bond state, first proposed in the context of triangular frustrated antiferromagnets in the 70's by P.W. Anderson. 

In the first part of my talk, I'll introduce frustrated antiferromagnets and some of the important parameters which lead to novel fundamental states such as spin ice, spin liquids and other similar ground states. I'll review some of the key experimental systems and experiments.

In the second part, I'll focus on spin liquids and will review in more details the relevance of the dynamical and static information brought by local techniques such as Nuclear Magnetic Resonance and Muon Spin Rotation.

I'll finally give a brief overview on a recently synthesized mineral, Herbertsmithite, ZnCu3(OH)6Cl2 which is the most promising candidate for a quantum spin liquid [Physics Today, February 2007].

The lecture will be given in English.

http://old-www.u-psud.fr/anglais.nsf/index.htm!OpenPageUniversity Paris-Sud 11 Orsay, France

We look forward to meeting you at the "Kolokvij na IJS"!

____________________________________
Marta Vidrih, univ.dipl.ekon.
F5 - Odsek za fiziko trdnih snovi
Institut "Jožef Stefan", Jamova 39, Ljubljana
tel: 01 477 39 02
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