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Studiul relaxarii magnetizarii ireversibile in supraconductorii puternic dezordonati

Studiul relaxarii magnetizarii ireversibile in supraconductorii puternic dezordonati. Ion Ivan. Perfect conductor. Meissner effect. Magnetic field destroys s/c. Electric current destroys s/c. I c. B c. 0. Proprietatile supraconductorilor. Vortices state in HTS.

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Studiul relaxarii magnetizarii ireversibile in supraconductorii puternic dezordonati

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  1. Studiul relaxarii magnetizarii ireversibile in supraconductorii puternic dezordonati Ion Ivan

  2. Perfect conductor Meissner effect Magnetic fielddestroys s/c Electric currentdestroys s/c Ic Bc 0 Proprietatile supraconductorilor

  3. Vortices state in HTS -Topirearetelei de vortexuriAbrikosovintr-un lichid de vortexuri la Tm -Centrii de fixare a vortexurilorsunteficienti in cazul solidului de vortexurisipracticineficientipentru un lichid de vortexuri -Pentru un solid de vortexurieficientacentrilor de fixare (existentaunuidensitaticritice de curent finite) se termina la linia de ireversibilitate, definita ca linia in diagrama (H, T) deasupracareia nu existahisterezis in curbele de magnetizare

  4. Thermal fluctuation and vortex lattice melting T <Tm T >Tm Lindemann criterion Phys. Rev. Lett. 80, 2693 The drunken walk of vortices

  5. B J FL Flux pinning in HTS Vortex captat intr-un centru pining Forta Lorentz care actioneaza pe unitatea de lungime a vortexului *V. Dolocan, Supraconductibilitatea-Principii fizice si aplicatii,Ed.Univ.Bucuresti,1997.

  6. Magnetization curves, critical currents Materiale feromagnetice Supraconductori n – numarul de vortexuri pe unitatea de suprafata

  7. Enhanced critical current density Ybco-LiCl neutron iradiated

  8. Vortex dynamics Kim-Anderson model Lege tip Arrhenius I=0 • Modelul Kim-Anderson I >0 U = U0JBVx U = U0 (1 – J/JC)

  9. Magnetization relaxation in HTS J < Jc J = Jc J > Jc

  10. Logaritmic vs non-logaritmic relaxation • Kim-Anderson model U = U0 (1 –J/JC) • Colective creep model

  11. Creep crossover rata de relaxare normalizata - la tempratura de crossoverM(t)=M(0)(t/t0)-s, S=KT/Uc U * arata eficienta piningului la T=Tcr -creep elastic -creep plastic

  12. Magnetization relaxation in MgB2 click -Creep elastic -Creep plastic

  13. Non-diverging pinning barrier at very low J Maley technique dM/dt exp[U(J)/T], U(J) = – T[ln(dM/dt) C]

  14. Magnetization relaxation in Y-123 thin films, sputter deposited • H = aT2, • Strat Y-123 depus pe SrTiO3 a 1.2 104 kOe K2

  15. Magnetization relaxation in Y-123 thin films, PLD deposited

  16. c axis 1D-APCs Magnetization relaxation in YBCO-BZO thin films, PLD deposited • Filmele au fost depuse prin PLD, pe un substrat MgO orientat (100) • cu buffer SrTiO3 (STO) folosind un laser cu excimer Lambda Physik • KrF (λ = 248 nm), avand o energie de 340 mJ/puls si • o presiune partiala de oxigen de 200 mTorr. Strat YBCO Buffer SrTiO3 -diametru nano-rod BaZO3 Substrat MgO -distanta medie intre doua nanorod-uri ZrO2 – stabilizat cu Y2O3 Pentru straturile cu centrii de fixare columnari se observa o crestere cu 100% a densitatii critice de curent, fata de straturile YBCO simple. Temperatura critica a fost obtinuta masurand m(T). Se observa o scadere nesemnificativa cu 4 0C pentru YBCO-BZO.

  17. Magnetization relaxation in YBCO-BZO thin films, PLD deposited Ep = Eel la T = Tcr EpU(J) ~ Tln(tw/t0) Tcr H1/2 EelH1/2

  18. CONCLUSION Pentru toate straturile YBCO, probele cu centrii de fixare columnari BZO, prezinta cel mare pinning

  19. Va multumesc !!!

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