ɑɚɫɬɶ 2. ȼɕɋɈɄɈɌȿɆɉȿɊȺɌɍɊɇȺə ɋȼȿɊɏɉɊɈȼɈȾɂɆɈɋɌɖ
Ɍɚɤɠɟ ɜɨɡɦɨɠɧɨ ɨɰɟɧɢɬɶ ɯɚɪɚɤɬɟɪɧɭɸ ɷɧɟɪɝɢɸ ' ɢɡ ɬɨɝɨ,
ɱɬɨ ɨɧɚ ɞɨɥɠɧɚ ɛɵɬɶ ɫɨɩɨɫɬɚɜɢɦɚ ɫ ɝɥɭɛɢɧɨɣ ɷɮɮɟɤɬɢɜɧɨɣ ɩɨɬɟɧ-
ɰɢɚɥɶɧɨɣ ɹɦɵ, ɚɬɚ, ɜ ɫɜɨɸ ɨɱɟɪɟɞɶ, ɫ ɯɚɪɚɤɬɟɪɧɨɣ ɤɢɧɟɬɢɱɟɫɤɨɣ
ɷɧɟɪɝɢɟɣ ɜ ɷɬɨɣ ɹɦɟ . ɉɨɥɚɝɚɹ, ɱɬɨ ɞɵɪɨɱɧɵɟ ɧɨɫɢɬɟɥɢ
ɢɦɟɸɬ ɛɨɥɶɲɭɸ ɷɮɮɟɤɬɢɜɧɭɸ ɦɚɫɫɭ m
2*2
2/
mag
m [!
*
~ ~10–30m, ɧɚɯɨ-
ɞɢɦ
'~300–500 K. ɂ, ɧɚɤɨɧɟɰ, ɦɨɠɧɨ ɨɰɟɧɢɬɶ T
22
2/ Ja!
c
ɤɚɤ ɬɟɦɩɟɪɚɬɭɪɭ
ɛɨɡɟ-ɤɨɧɞɟɧɫɚɰɢɢ, ɢ ɩɨɥɭɱɢɬɶ T
c
~100 K.
ɒɪɢɮɮɟɪ ɬɚɤɠɟ ɭɱɟɥ, ɱɬɨ ɢɦɟɸɬ ɦɟɫɬɨ ɭɫɥɨɜɢɹ ɧɟɫɬɢɧɝɚ, ɢ
ɩɨɥɭɱɢɥ ɫɩɚɪɢɜɚɧɢɟ ɧɚ ɮɨɧɟ ɬɚɤɢɯ ɜɨɥɧ ɫɩɢɧɨɜɨɣ ɩɥɨɬɧɨɫɬɢ
(SDW), ɬɚɤ ɱɬɨ ɫɢɦɦɟɬɪɢɹ ɫɜɟɪɯɩɪɨɜɨɞɹɳɟɝɨ ɩɚɪɚɦɟɬɪɚ ɩɨɪɹɞɤɚ
ɨɤɚɡɚɥɚɫɶ ɬɢɩɚ ɫɢɦɦɟɬɪɢɢ d-ɫɩɚɪɢɜɚɧɢɹ. ɒɪɢɮɮɟɪ ɤɚɱɟɫɬɜɟɧɧɨ
ɨɩɢɫɵɜɚɟɬ ɮɚɡɨɜɭɸ ɞɢɚɝɪɚɦɦɭ ɩɨ ɤɨɧɰɟɧɬɪɚɰɢɢ ɧɨɫɢɬɟɥɟɣ, ɤɨɬɨɪɚɹ
ɩɪɚɤɬɢɱɟɫɤɢ ɷɤɜɢɜɚɥɟɧɬɧɚ ɞɢɚɝɪɚɦɦɟ ɩɨ ɤɨɧɰɟɧɬɪɚɰɢɢ ɞɨɩɢɪɨɜɚ-
ɧɢɹ ɤɢɫɥɨɪɨɞɨɦ ɢɥɢ ɫɬɪɨɧɰɢɟɦ ɜ ȼɌɋɉ (
ɫɦ. ɪɢɫ. 3.7). Ɍɚɤɚɹ ɦɨɞɟɥɶ
ɟɫɬɟɫɬɜɟɧɧɵɦ ɨɛɪɚɡɨɦ ɨɩɢɫɵɜɚɟɬ ɢ ɞɢɷɥɟɤɬɪɢɡɚɰɢɸ ɫɢɫɬɟɦɵ ɩɪɢ
ɭɦɟɧɶɲɟɧɢɢ ɞɨɩɢɪɨɜɚɧɢɹ, ɢ ɚɧɬɢɮɟɪɪɨɦɚɝɧɟɬɢɡɦ, ɢ ɧɟɤɨɬɨɪɵɟ
ɚɧɨɦɚɥɢɢ ɜ ɫɩɟɤɬɪɚɯ ȼɌɋɉ.
ɂɡ ɦɚɝɧɢɬɧɵɯ ɦɟɯɚɧɢɡɦɨɜ ɧɚɢɛɨɥɟɟ ɢɡɜɟɫɬɧɚ ɦɨɞɟɥɶ ɪɟɡɨ-
ɧɚɧɫɧɵɯ ɜɚɥɟɧɬɧɵɯ ɫɜɹɡɟɣ (RVB – resonance valence bonds)
Ɋ.ȼ. Ⱥɧɞɟɪɫɨɧɚ [77]. Ⱥɧɞɟɪɫɨɧ ɩɪɟɞɩɨɥɨɠɢɥ, ɱɬɨ ɨɫɧɨɜɧɨɟ ɫɨɫɬɨɹ-
ɧɢɟ ɝɚɦɢɥɶɬɨɧɢɚɧɚ (6.1) ɜ ɞɜɭɦɟɪɧɨɦ ɫɥɭɱɚɟ ɧɟ ɧɟɟɥɟɜɫɤɨɟ ɫ <S
Z
>=0
ɢ ɪɚɡɞɟɥɟɧɢɟɦ ɩɨ ɩɨɞɪɟɲɟɬɤɚɦ, ɚɞɪɭɝɨɟ, ɜ ɤɨɬɨɪɨɦ ɪɚɜɟɧ ɧɭɥɸ
ɩɨɥɧɵɣ ɦɚɝɧɢɬɧɵɣ ɦɨɦɟɧɬ <S
tot
>=0. Ɏɭɧɞɚɦɟɧɬɚɥɶɧɨɟ ɨɬɥɢɱɢɟ ɟɝɨ
ɨɬ ɧɟɟɥɟɜɫɤɨɝɨ – ɜ ɷɥɟɦɟɧɬɚɪɧɵɯ ɜɨɡɛɭɠɞɟɧɢɹɯ. ȿɫɥɢ ɜ ɩɟɪɜɨɦ ɫɥɭ-
ɱɚɟ ɷɬɨ ɨɛɵɱɧɵɟ ɫɩɢɧɨɜɵɟ ɜɨɥɧɵ, ɦɚɝɧɨɧɵ, ɬɨ ɭ Ⱥɧɞɟɪɫɨɧɚ – ɧɟɥɢ-
ɧɟɣɧɵɟ ɬɨɩɨɥɨɝɢɱɟɫɤɢɟ ɜɨɡɛɭɠɞɟɧɢɹ (ɮɟɪɦɢɟɜɫɤɨɝɨ ɬɢɩɚ), ɧɚɡɜɚɧ-
ɧɵɟ ɫɩɢɧɨɧɚɦɢ (spinon), ɤɨɬɨɪɵɟ ɪɨɠɞɚɸɬɫɹ ɢ ɭɧɢɱɬɨɠɚɸɬɫɹ ɬɨɥɶ-
ɤɨ ɩɚɪɚɦɢ.
ɇɚ ɪɢɫ. 6.3 ɫɯɟɦɚɬɢɱɧɨ ɞɚɧɨ ɩɪɟɞɫɬɚɜɥɟɧɢɟ ɨ ɫɩɢɧɨɧɟ ɢ
RVB-ɫɨɫɬɨɹɧɢɢ. Ȼɥɚɝɨɞɚɪɹ ɜɵɪɨɠɞɟɧɢɸ ɜɨɥɧɨɜɵɯ ɮɭɧɤɰɢɣ
(ɩɨɥɭ-
ɱɚɟɦɵɯ ɢɡ ɧɚɛɨɪɚ ɞɢɦɟɪɨɜ ɫ ɩɚɪɚɦɢ ɩɪɨɬɢɜɨɩɨɥɨɠɧɨ ɧɚɩɪɚɜɥɟɧɧɵɯ
ɫɩɢɧɨɜ) ɩɨ ɮɚɡɟ (ɢɡ-ɡɚ ɫɜɨɛɨɞɵ ɜɵɛɨɪɚ ɜɜɟɪɯ-ɜɧɢɡ ɢɥɢ ɜɧɢɡ-ɜɜɟɪɯ)
ɷɥɟɦɟɧɬɚɪɧɨɦɭ ɜɨɡɛɭɠɞɟɧɢɸ ɫɨɨɬɜɟɬɫɬɜɭɟɬ ɧɟɫɩɚɪɟɧɧɵɣ ɫɩɢɧ (ɜ
ɫɥɭɱɚɟ ȼɌɋɉ ɫɜɨɛɨɞɧɚɹ ɜɚɥɟɧɬɧɨɫɬɶ – ɞɵɪɤɚ), ɚ ɟɝɨ ɩɟɪɟɯɨɞɭ ɫ ɦɟɫ-
ɬɚ ɧɚ ɦɟɫɬɨ – ɩɟɪɟɛɪɨɫ ɜɚɥɟɧɬɧɨɫɬɢ (ɞɜɢɠɭɳɚɹɫɹ ɜɚɥɟɧɬɧɚɹ ɫɜɹɡɶ,
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