Macroscopic quantum effects generated by the acoustic wave in a molecular magnet

Transcription

1 Cudnovsky-Fes Mcroscopc qunum effecs genered by e cousc wve n moleculr mgne Gwng-Hee Km ejong Unv., Kore Eugene M. Cudnovksy Lemn College, CUNY Acknowledgemens D. A. Grnn Lemn College, CUNY

2 Oulne ysem of neres nd MM Prevous eorecl work b spn oscllons genered by ulrsound n solds Mcroscopc qunum effecs genered by e cousc wve n MM Mcroscopc qunum bes of M Cnge of e se of e M sep Possbly of expermen n MM ummry

3 ysems of Ineres Nno-prcle Ferrn ngle Molecule nm 3nm nm nm

4 ngle Molecules Mn 0 Fe8 0 V5 / Fe0 0 Mn6 44 V6 /,3/ [Mn4] 9/9/

5 Qunum spn unnelng nd pse nerferencemn nd Fe8 esy xs A Z Mn 0 Fe8 0 X rd xs ϕ H B Y [Fredmn e l, PL 996 Toms e l, Nure 996] [C. ngregoro, e. l. PL 997] [A. Grg, EPL 993; Wernsdorfer nd essol, cence, 999]

6 Prevous eorecl workb spn oscllon To sudy qunum spn-roon effecs n sold, we need o esme e mgnec feld due o roon. δφ r u r,, [Clero nd Cudnovsky, PL, 99, ] e ponon dsplcemen feld e locl roon of e crysl lce Ω r u& r,, Ω u0 B ~ f ~ 0 γ γ λ Guss f ~ 3 u0 ~ GH nm

7 b pn Oscllon Con d For dsplcemen feld n surfce cousc wve, one obns δφ c k y r, u0e cos kx δφ x, In e presence of deformon of e crysl lce, locl nsoropy xes defned by e crysl feld re roed by e ngle. H e δφ δφ H Ae H D H A rns Lborory frme Lce frme Ψ l δφ e Ψ

8 b pn Oscllon Con d Te lce-frme Hmlonn l H H A Ω Ω c k y δφ u e sn kx 0 Te b oscllon beween e wo lowes ses of Ĥ A φ ± ± ± ± ± m m

9 Projec e Hmlonn on e l eff b pn Oscllon Con d ± sn σ kx σ 3 k y u0e c ong wve pproxmon l Ψ C ses φ C φ 0, 0 0 C 0, x 0 C C C Ω e Ω Ω sn / Ω cos sn e, Ω Ω /

10 b pn Oscllon Con d Te expecon vlue of e projecon of e spn ono e Z xs Ω Ω Ω Ω Ψ Ψ x K kx x K kx sn cos sn sn Ω k K ~ Ω ~ / 0.9, 0. 0, 0, x

11 b pn Oscllon Con d Te b oscllons of 0, 0, dx x x v λ λ ve wve dependence on coordne Ŝ Ψ kx l l eff 3 sn σ σ l l eff l Ψ Ψ sn sn & & sn sn & & 0 x / λ x, x x x, / 0, λ!!

12 Mcroscopc qunum effec genered by e cousc wve n MM Feld weep How cn you obn e globl b oscllons verged over e wole smple? λ, 0, x dx v x λ 0 l eff σ [ gµ sn ] Bc kx σ δe c dh d

13 Feld sweepcon d d d kx p qp d d sn τ τ γτ τ l l eff l Ψ Ψ [ ] Ψ kx c g l B l eff 3 sn σ µ σ were µ γ τ B q p c g, /,,, x dx x x v λ λ 0,,

14 Feld sweepcon d Te feld s cngng consn re γ nd pulse of sound s nroduced sorly before recng e resonnce beween ± Ω, γ,

15 Feld sweep con d Te fnl mgneon on crossng e sep

16 Feld sweep con d Anoer possble suon corresponds o e sysem nlly sured n e -> se, fer wc e cousc wve s ppled o e sysem nd mnned durng e sweep. M M M d d kx p qp M d d sn τ η τ γτ τ Γ M M M, η e level provdes sgnfcn probbly of e rnson

17 Feld sweep con d

18 Feld sweep con d Te opml condon for pronounced bes qp γ W does e bove condon men for expermen? π λ 0 c q u c q u π λ 0 Te vldy of e connuous elsc eory λ << 0 u < q

19 Feld sweepcon d nce expermens on MM requre T~OK, we sould be concerned w e power of e sound. I sould be suffcenly low o vod e unwned eng of e smple. s kg c MH f s cm c cm g / 0.5 / 0 / 5 3 ρ 3 0 / cm W q c c u A P ρ ρ q u π λ 0 ex Fe8

20 Feld sweepcon d

21 ummry -Te se of e mgneon sep due o resonn spn unnelng n MM cn be srongly ffeced by sound. - Te cousc wve cn lso genere qunum bes of e mgneon durng feld sweep. - Te requred frequency nd power of e sound, nd e requred sweep re re wn expermenl rec. f 0.5 MH P / A 0. kw / cm c kg / s

22 Hppy 60 brdy, Eugene!

23 Dsorder produces rndomness n e locl feld. M H H δh x c ξ gµ B δh x Te crcl sreng of dsorder wc e bes dspper ξ ~

24 -Te feld sweep n MM s ccompned by e self-orgnon of e dpolr feld suc e exernl feld n e crysl mnns very g degree of unformy. [Grnn nd Cudnovsky, PL 009] -egrdless of s effec, our predcon e sympoc vlue of exbs sgnfcn decrese n e presence of e sound, s no ffeced by dsorder.

25 Feld sweep

26 Feld sweep