Anomalous magnetism and 209 Bi nuclear spin relaxation in Bi 4 Ge 3 O 12 crystals V.G. Orlov 1 , E.A. Kravchenko 2 , Tetsuo Asaji 3 , G.S. Sergeev 1 , Yu.F. Kargin 4 , A.N. Vasil’ev 5 , O.S. Volkova 5 1 Russian Research Center “Kurchatov Institute”, Moscow, Russia 2 Institute of General and Inorganic Chemistry, Moscow, Russia 3 Department of Chemistry, College of Humanities and Sciences, Nihon University, Tokyo, Japan 4 State Institute of Metallurgy and Material Science, Moscow, Russia 5 Lomonosov Moscow State University, Moscow, Russia
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1 Russian Research Center “Kurchatov Institute”, Moscow, Russia
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Anomalous magnetism and 209Bi nuclear spin relaxation in Bi4Ge3O12 crystals
1Russian Research Center “Kurchatov Institute”, Moscow, Russia 2Institute of General and Inorganic Chemistry, Moscow, Russia 3Department of Chemistry, College of Humanities and Sciences, Nihon University, Tokyo, Japan 4State Institute of Metallurgy and Material Science, Moscow, Russia5Lomonosov Moscow State University, Moscow, Russia
E.A. Kravchenko, V.G. Orlov et al., JETP Lett. 86 (2007)
Bi4Ge3O12
1 1 11 1 1( ) ( ) ;l eT T T
1 1 1 1 11 1 1 1 1
1 1 11 1
( ) ( ) ; ( ) ; ( ) ;
; exp( / );
nl e l e e
e e s e
T T T T b T T K
T T a T
V.G. Orlov T. Asaji E.A. Kravchenko et al. JETP 137 (2010)
Gd-doped Bi4Ge3O12
Nd-doped Bi4Ge3O12
0 0 0 0 4 4 0 0 4 42 2 4 4 4 4 6 6 6 6
ˆCEFH B O B O B O B O B O
0
5
20
25
Δ
meV
Conclusion
• A strong influence of minor amounts of paramagnetic dopand atoms on the relaxation processes of the 209Bi nuclear spin was observed for Bi4Ge3O12 crystals.
• Both weak external magnetic field and paramagnetic atoms inserted into the crystal lattice of Bi4Ge3O12 result in considerably increasing spin-spin relaxation time T2.
• In pure Bi4Ge3O12 crystal, intrinsic paramagnetic centers are found to exist which decrease the spin-lattice relaxation time T1 at low temperature.
• The crystal electric field splits the ground multiplet of the paramagnetic dopants and results in non-monotonous dependence of spin-lattice relaxation time T1 on temperature in the temperature interval 4.2-77 K.