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SmBa

₂

Cu

₃

O

_y

8 ý ¾ ¹ Åy ¢ ¤V R ËV ê s ¤; c 6 X ¢ Sm

³⁺

V ê s V R Ë T Æ X Ø8 ý ÇÊ Ý

T

+Ö<Ú · -> )o · Dawood Ahmad · »ZÌ x · z@B · »*åx^∗

Â

Òíß@/<Æ§ Óüto<Æõ, ÂÒíß 609-735 (2008¸ 8Z4 25{9 ~ÃÎ6£§)

¦:r í¸^ SmBa2Cu3Oy\"f gË>ÈÒU·s (λ) , çß[O$í U´s (ξ), ÂÒ e>l©õ °ú Ér í¸

\ P

%i<Æ&h :£¤$í©Ãº[þt\ @/ôÇ Sm³⁺s:r_ ´òõ\¦ ½¨ %i. Hao-Clem¸4Sqõ Bulaevskii-Ledvij- Kogan (BLK) ¸4SqÐ ÂÒ' κ=53.7, λab(0)=69.4 nm, Hc1(0)= 988.1 Oe _ %ò%i\ eH כ `¦ ·ú¤

. z´+«>õü< © ¸ú ´úH BCS dirty-limit s:rÜ¼Ð ÂÒ' >íß)a Hc2(0)°úכÉr 119.40 ± 6.9T %iÜ¼ 9 ξab(0) H 16.6 ± 0.5 ˚A%iHX< sכ Ér Y1Ba2Cu3Oy_ °úכõ q5pw %i. sכ Ü¼Ð ÂÒ' Sm³⁺s:r Ü

¼Ð sÀÒ#Q ©$í[þtÉr λab_ yè\H l# %itëß ξab\H _ o \O%36£§`¦ SX %i

.

PACS numbers: 74.72.Jt

Keywords: SmBa2Cu3Oy, Sm³⁺´òõ, í¸ ©Ãº

I. "e Â]Ø

BÐÀÓ í¸^ RBa2Cu3Oy (R-123, R : BÐÀÓ "é¶

è)H "é¶½¨¸ü< e>:r¸ (Tc) YBa2Cu3Oy(Y-123) ü

< q5pwôÇכ Ü¼Ð ·ú94R e [1,2]. ¸Ï?@1lxîß BÐÀÓ í

¸^Ð Y-123 \¦ @/^ l 0AK R-123 _ ~ÃÌ}s ´ú§s

½¨÷&%3HX< [3,4] :£¤y D¥½+Ë BÐÀÓ í¸ ~ÃÌ} (Nd, Eu, Gd) Ba2Cu3Oy [5]\ @/ôÇ ½¨\¦ :xK &ñ§>=÷&t ·ú§

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r (mismatch) éß0A[jí\ lôÇ ÂÒ&h pinning B

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R-123 _ âÄº Tc s \"f í¸$íõ ©$íÉr /BN

>

rôÇ. Y-123 _ ©$íH"é¶ ©`¦ sÀÒt ·ú§Ér Cu²⁺

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f ©$í ñ_ ÅÒכ¹ôÇ ÂÒìrÉr R³⁺ s:r\"f èß

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K Tc \¦ ]jü@ôÇ gË>ÈÒU·s (λ), çß[O$í U´s (ξ)ü< °ú

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r í¸ :£¤$í©Ãº\ %ò¾Ó`¦ z}9כ Ü¼Ð #.

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rëH\"fH R-123 í¸ ×æ\ SmBa2Cu3Oy \¦ ½+Ë$í

# \;¤r 5Åq\"f &ñ§>=r& Hao-Clem ¸4Sq [7]õ BLK

∗E-mail: [email protected]

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Ð ½+Ë$í %i. Sm2O3, BaO2, CuOìr´ú_ ílÓüt|9`¦

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r«Ñ\¦ ¸ú°ú ìr´úr«ÑÐ ëßHÊê 45 µm seiveÐ 5g

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f sכ `¦ ©\O6 x \;¤rü< ¸ú [O#Q ©:r\"f 5T_ l

Ð z´:r\"f SmBa2Cu3OyH c»¡¤õ ab ~½Ó¾Ó\ @/ôÇ ½¨

¸&h s~½Ó$íÜ¼Ð # y ~½Ó¾Ó\ Ér l ¸F'p à

Ô\¦ °úl M:ëH\ &ñ§>=s 0px . ¦l© \"f ìr

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_ &ñ§>=)a &ñ¸\¦ ·úÐl 0AK X- r]XÁº](\¦ ¸

K Ð¤HX< sM: s6 x)a targetÉr Cu_ Kα `¦ 6

x %i. s X ©u_ âÄº scaning 5Åq¸H 4^◦/ìr s

¦ 5Åq·úÉr 30 kV, ÀÓH 10 mA Ð %iÜ¼ 9 8£¤&ñ

# 3

0AH 10 ∼ 90^◦s.

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Fig. 1. (a) X-ray diffraction data for aligned grains of SmBa2Cu3Oy. (b) Zero field cooled (ZFC) and field cooled (FC) dc susceptibility versus temperature curves of the aligned SmBa2Cu3Ox measured under the mag- netic fields applied parallel to c axis (H||c) and ab plane (H||ab).

#

Qt :r¸ü< l© \"f í¸ ©IÐ_ s

:

r¸, o 1px`¦ %3l 0A # SQUID (Superconducting Quantum Interferece Device) §4>\¦ 6 x %i. 8£¤

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III. +sÇÊÝ õmÍ ÀXØ8ý

Fig. 1(a)H &ñ§>=)a SmBa₂Cu₃O_y_ &ñ§>=)a &ñ¸

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¦ ·úÐl 0A # X- r]X z´+«>`¦ 'ôÇ õs.

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Fig. 2. (a) Magnetization curves of the aligned SmBa2Cu3Oy, measured in the temperature region of 10-300 K and under the fields of 1-6 T, with a step of 0.5 T. (b) Magnetic susceptibility versus C/(T − Θ) curves above Tc in the field of 1-6 T, where C and Θ are con- stants. Here, the unit of susceptibility is emu/(cm³ Oe).

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H ab\ ¨î' > (H||ab) 8£¤&ñ)a o°úכÐ 2C&ñ

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Fig. 2(a)H c»¡¤\ ¨î'ôÇ #Q l©\"f :r¸\

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r o°úכ`¦ 8£¤&ñôÇכ s. Tc0A\"f ÷rëßm Tc A

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Ç 7áxÀÓ_ M(T)/BGÉr íl_ BÐÀÓ í¸^ ½¨\

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¦ %3Ér Êê sכ `¦ s6 x # T < Tc\"f ©$í ñ\¦ ]

jôÇ Êê íHÃºôÇ í¸ ñ\¦ %3%3.

Fig. 2(b)\"f ÐH ü< °ú s T > Tc \"f :r¸\

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r oÖ¦ (χ = M/H) `¦ 6£§õ °ú Ér dÜ¼Ð ?/%3

.

χ(T ) = χ0+ C

T − Θ (1)

#

l"f χ0 (=5.81 × 10⁻⁶ ±6.45 × 10⁻⁷ emu/cm³ Oe)

H Ùþd ìøÍ$í (core diamagnetic), Pauliü< Van Vleck

(3)

Fig. 3. Magnetization versus temperature curves after the paramagnetic signals are eliminated and Ms(T ) measured in the fields of 1-6 T with a step of 0.5 T. The inset shows the crossover of the Ms(T ) curves near Tc.

l

# 1px_ ½+Ës¦, C (=1.16 × 10⁻³ ± 6.10 × 10⁻⁵ K emu/cm³ Oe) H Curie-Weiss ©Ãº, Θ (=-58.98 ± 11.16 K) H Curie-Weiss :r¸s. Curie-Weiss ZOgË:Ér Ér

BÐÀÓ í¸^\¸ ¸ú ´úH כ Ü¼Ð ·ú94R e.

Fig. 3Ér íHÃºí¸ o Ms(T )(= M (T )−Mp(T ))_

:

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©$í o°úכÜ¼Ð d(1)ÐÂÒ' %3#Q&. Fig. 3_

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H z´+«>°úכ[þts 5g"f § H ôÇ &hs e. § &h\

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f H Ms ü< T _ °úכ[þtÉr 4π M^∗ ≈-0.35 G s

¦ T^∗≈ 89.98 K s. sQôÇ 7áxÀÓ_ § H Tl ¢¸H Bi

í¸^ [10,11]ü< °ú Ér 2Dí¸^\"f Ð Ìº§Â >

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½ +

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.

M (T, H) = − φ0

32π²λ²lnηHc2

eH +kBT

φ0s ln16πkBT κ² αφ₀sH√

e (2)

#

l"f φ0=2.0678 × 10⁻⁷ gauss cm², e = 2.718, η =1.4 [7, 12, 13], γ²Ér l¸F'pàÔ_ q mc/mab, sH s _

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f ab\ @/ôÇ gË>ÈÒU·s (λab). 'Í P: ½ÓÉr §êøÍ÷&

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§ &h (M^∗, T^∗)Ér ∂M/∂(ln H)=0Ü¼Ð ÂÒ' ½¨½+É Ãº e

.

M^∗(T^∗) = −kBT φ0s ln ηα

√e (3)

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z´+«> °úכ`¦ @/{9 # q§<ÊÜ¼Ð"f κ(T ) ü< Hc(T ) \¦

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¨½+É Ãº e.

Fig. 4(a)H Hao-Clem ìr$3Ü¼Ð ÂÒ' ½¨ôÇ κ(T )\¦ Ð

#

V ê s V R Ë T Æ X Ø8 ý  ÇÊ Ý

SmBa

Cu

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V ê s V R Ë T Æ X Ø8 ý  ÇÊ Ý

V ê s V R Ë T Æ X Ø8 ý ÇÊ Ý

8 ý ¾ ¹ Åy ¢ ¤V R ËV ê s ¤; c 6 X ¢ Sm

V ê s V R Ë T Æ X Ø8 ý ÇÊ Ý