( 2001MB062) Zachary Fisk Thomas Maurice Rice Hans Rudolf Ott MgB Y 2 C 3 18K 11K Ca EuB 6 CaB 6 CaB 2 C 2 MgB 2 Y 2 C 3 1 NED

Size: px

Start display at page:

Download "( 2001MB062) Zachary Fisk Thomas Maurice Rice Hans Rudolf Ott MgB Y 2 C 3 18K 11K Ca EuB 6 CaB 6 CaB 2 C 2 MgB 2 Y 2 C 3 1 NED"

ちえこなかじゅく
5 years ago
Views:

1 ( 2001MB062) Zachary Fisk Thomas Maurice Rice Hans Rudolf Ott MgB Y 2 C 3 18K 11K Ca EuB 6 CaB 6 CaB 2 C 2 MgB 2 Y 2 C 3 1 NEDO 2 MgB MgB 2 NEDO MgB 2 σ π MgB 2 [1] MgB 2 [2] 2- CaB 6 Ott Fisk 1999 CaB 2 C 2 [3] µsr

2 NMR Fe Fe CeB 6 Eu 1 x Ca x B 6 [4] Mg [5] NEDO 2 MgB 2 NEDO MgB 2 σ π 2.1 MgB 2 MgB 2 κ [6] 0.2mm κ(t ) 2 T κ(h) σ MgB 2 Mg(B 0.94 C 0.06 ) 2 Wiedemann-Franz 1 Wiedemann-Franz MgB 2 Wiedemann-Franz 1: Wiedemann-Franz

3 2.2 MgB 2 T c Γ E 2g ( ) B 1g Al MgB 2 Al 2.3 MgB 2 Mg MgB MgB V σ V π σ π V H c2 π 2 c- H c2 c- H a,b c2 20% T BCS H c BCS NEDO W 7 Re 13 X (X=B C) 7 K Re β-mn ( P ) II H c1 (0) H c2 Ginzburg-Landau (GL) X=B 7.7 mt 11.4T 54 X=C 4.0 mt 12.6T 80 X=B C

2: 2- H c2 2/k B T c = 4.28 4.02 T c s- B C β-mn Y 2 C 3 18 K [7] Krupka [J. Less-Common Met.

4 2: 2- H c2 2/k B T c = T c s- B C β-mn Y 2 C 3 18 K [7] Krupka [J. Less-Common Met. 17 (1969) 91] 11.5 K Y 2 C 3 Pu 2 C 3 II (H c1 (0)) 3.5 mt T c 15 K 18 K Krupka Y 2 C 3 T c 3 Pu 2 C 3 3: Y 2 C 3 18 K

5 4 4.1 CaB 6 CaB 6 (ARPES) ARPES X 1eV X (4 5) cm 3 [2] 4.2 CaB 6 1:1 Ca:Fe Al B T c < 50K Fe 0.1% Fe Mn, Co, Ni La (Ca:La 1:.005) 1:1 Ca:Fe 300 K La Fe CaB 6 1 emu Fe Co 300K La Fe 4.3 Eu 1 x Ca x B 6 Eu Ca Ca x Ca x = 0.75 x = 0.4 ρ(t, H) R H (T, H) ρ M ρ = ρ(0) exp(βm) 2 ρ M R H = R 0 + R [1 exp{ α(m M 0 )}]θ(m M 0 ) R 0 M 0 2 K 200 K 70 koe 4 [8]

6 4: Eu 1 x Ca x B 6 Ca (x) x 4.4 EPR NMR EPR g = 2 EPR 450 K SmB 6 50 K SmB 6 Sm 1 emu/ CaB 6 NMR ppm 300 7K BaB K MB 6 M=Sr Ca Ba H CaB 2 C 2 13 C CaB 2 C 2 13 C NMR 13 C NMR 13 C I = 1/2 13 C NMR 13 (1/T 1 ) 9 13 (1/T 1 ) (1/T 1 ) (1/T 1 ) 300 K 9 10 K

7 13 (1/T 1 ) 300 K 13 (1/T 1 ) CaB 2 C CaB 6 CaB 6 Ca U U Ca U B 6 T =17 K 0.8K T 2 5 [9] U LaB K 5: U Ca B 6 ( 17 K 20 K 5 LaB 6 BaB BaB 6 LaB 6 LaB 6 f 4f NEDO CeB CeB 6 Ce 1 x La x B 6 CeB 6

8 Ce 1 x La x B 6 IV Ce 0.7 La 0.3 B 6 (µsr) [10] IV IV 2 III IV 5.2 CeB 6 [11] [12] 5.3 Ce 1 x La x B 6 Ce x La 1 x B 6 IV Γ 5u octupole [111] Γ 8 Γ 5u 3 2 Γ 5u Γ 5g IV [13] X 6 NEDO MgB 2 2 Y 2 C 3 W 7 Re 13 X (X=B or C) Eu 1 x Ca x B 6 Ca 1 x U x B 6 Ce 1 x La x B 6 NEDO NEDO

9 [1] T. Ekino, T. Takasaki, T. Muranaka, J. Akimitsu, and H. Fujii, Tunneling spectroscopy of the superconducting gap in MgB 2, Phys. Rev. B (2003). [2] S. Souma, H. Komatsu, T. Takahashi, R. Kaji, T. Sasaki, Y. Yokoo, and J. Akimitsu, Electronic Band Structure and Fermi Surface of CaB 6 Studied by Angle-Resolved Photoemission Spectroscopy Phys. Rev. Lett (2003). [3] J. Akimitsu, K. Takenawa, K. Suzuki, H. Harima and Y. Kuramoto, High-temperature ferromagnetism in CaB 2 C 2, Science 293, 1125 (2001). [4] G. A.Wigger, C. Beeli, E. Felder, H.R. Ott, A.D. Bianchi and Z. Fisk, Percolation and the Colossal Magnetoresistance of Eu-Based Hexaboride, Phys. Rev. Letters 93, (2004). [5] S. Watanabe, K. Kusakabe and Y. Kuramoto, Partial Ferromagnetism in Semimetallic Systems: Numerical Calculation and Rigorous Proof, Physica B , 811 (2002). [6] A. V. Sologubenko, J. Jun, S. M. Kazakov, J. Karpinski, and H. R. Ott, Thermal conductivity of single-crystalline MgB 2, Phys. Rev. B 66, (2002). [7] G. Amano, S. Akutagawa, T. Muranaka, Y. Zenitani and Jun Akimitsu, Superconductivity at 18 K in Yttrium Sesquicarbide System, Y 2 C 3, J. Phys. Soc. Jpn (2004). [8] A. Perucchi,G. Caimi, H. R. Ott, L. Degiorgi, A. D. Bianchi, and Z. Fisk, Optical Evidence for a Spin-Filter Effect in the Charge Transport of Eu 0.6 Ca 0.4 B 6, Phys. Rev. Lett. 92, (2004). [9] G.A. Wigger, E. Felder, S. Weyeneth, H.R. Ott, Z. Fisk, Kondo Behavior of U in CaB 6, eprint arxiv:cond-mat/ , Europhysics Letters (in press). [10] H. Takagiwa, K. Ohishi, J. Akimitsu, W. Higemoto, R. Kadono1, M. Sera and Satoru Kunii, Magnetic Properties in Phase IV of Ce 0.7 La 0.3 B 6 Studied by Muon Spin Relaxation, J. Phys. Soc. Jpn. 71, 31 (2002). [11] H. Kusunose and Y. Kuramoto, Non-Collinear Magnetism due to Orbital Degeneracy and Multipolar Interactions, J. Phys. Soc. Jpn. 70, 1751 (2001). [12] G. Sakurai and Y. Kuramoto, Multipolar Interactions in the Anderson Lattice with Orbital Degeneracy, J. Phys. Soc. Jpn. 73, (2004). [13] K. Kubo and Y. Kuramoto, Octupole Ordering Model for the Phase IV of Ce x La 1 x B 6, J. Phys. Soc. Jpn. 73, 216 (2004). [14] H. Kusunose and T.M. Rice, Single Particle Spectrum in Electron Doped Cuprates, Phys. Rev. Lett. 91, (2003).

10 [15] Y. Maeno, T.M. Rice, M. Sigrist The intriguing superconductivity of strontium ruthenate, Phys. Today 54, 42 (2001). [16] T. Maehira, T. Hotta, K. Ueda, and A. Hasegawa Electronic Structure and the Fermi Surface of PuCoGa 5 and NpCoGa 5 Phys. Rev. Lett. 90, (2003). [17] T. Takimoto, T. Hotta and K. Ueda, Strong-coupling Theory of Superconductivity in a Degenerate Hubbard Model, Phys. Rev. B69, (2004). [18] K. R. Thurber, K. M. Shen, A. W. Hunt, T. Imai, and F. C. Chou, 17 O NMR study of the local charge state in the hole-doped Cu 2 O 3 two-leg spin-ladder A 14 Cu 24 O 41 (A 14 = La 6 Ca 8, Sr 14, Sr 11 Ca 3, Sr 6 Ca 8 ), Phys. Rev. B 67, (2003). [19] P. M. Singer and T. Imai, Systematic 63 Cu NQR and 89 Y NMR Study of Spin Dynamics in Y 1 z Ca z Ba 2 Cu 3 O y across the Superconductor-Insulator Boundary, Phys. Rev. Lett. 88, (2002). [1] [2]

d > 2 α B(y) y (5.1) s 2 = c z = x d 1+α dx ln u 1 ] 2u ψ(u) c z y 1 d 2 + α c z y t y y t- s 2 2 s 2 > d > 2 T c y T c y = T t c = T c /T 1 (3.

d > 2 α B(y) y (5.1) s 2 = c z = x d 1+α dx ln u 1 ] 2u ψ(u) c z y 1 d 2 + α c z y t y y t- s 2 2 s 2 > d > 2 T c y T c y = T t c = T c /T 1 (3. 5 S 2 tot = S 2 T (y, t) + S 2 (y) = const. Z 2 (4.22) σ 2 /4 y = y z y t = T/T 1 2 (3.9) (3.15) s 2 = A(y, t) B(y) (5.1) A(y, t) = x d 1+α dx ln u 1 ] 2u ψ(u), u = x(y + x 2 )/t s 2 T A 3T d S 2 tot S