Anomalous magnetism and 209Bi nuclear
spin relaxation in Bi4Ge3O12 crystals
V.G. Orlov1, E.A. Kravchenko2, Tetsuo Asaji3,
G.S. Sergeev1, Yu.F. Kargin4, A.N. Vasil’ev5, O.S. Volkova5
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, Russia
5Lomonosov Moscow State University, Moscow, Russia
BikAlOmXn (A =Al, B, Ge, Ba; X = Cl, Br)
Hloc ≤ 250 G ;
E.A. Kravchenko, V.G. Orlov, M.P. Shlykov
Russian Chem. Rev. 75 (2006)
E.A. Kravchenko, V.G. Orlov et al., JETP Lett. 86 (2007)
α-Bi2O3
V.I. Nizhankovskii, A.I. Kharkovskii, V.G. Orlov
Ferroelectrics 279 (2002)
T = 4.2 K; H || c; ▲– ZFC; □ – FC, H = 284 Oe; Δ – FC, H = 566 Oe;
M (10 G.cm /g)
-5
3
500
400
300
200
100
0
1000
2000
H (Oe)
3000
4000
α-Bi2O3
V.I. Nizhankovskii, A.I. Kharkovskii, V.G. Orlov
Ferroelectrics 279 (2002)
-2
2
P (10 esu/cm )
2
1
0
50
H (kOe)
100
150
In2Te powder 77K
In(1) ν2=15.12 MHz
Bi4Ge3O12
E.A. Kravchenko, Yu.F. Kargin,
V.G. Orlov, T. Okuda, K. Yamada,
JMMM 224 (2001)
E.A. Kravchenko, V.G. Orlov et al.,
JETP Lett. 86 (2007)
Bi4Ge3O12
E.A. Kravchenko, V.G. Orlov
et al., JETP Lett. 86 (2007)
I ( , H ext , T )
A( , H ext , T )  exp( / T2 )
Pure, H=0 Pure, H=30 Oe Gd-doped Nd-doped Pr-doped
,
T2 μsec
50
100
220
400
400
Bi4Ge3O12
V.G. Orlov
T. Asaji
E.A. Kravchenko
et al.
JETP 137 (2010)
T11  (T11 )l  (T11 ) e ;
T11  (T11 )l  (T11 )e ;
(T11 )l  b  T n ;
 e1  T1e 1   s1 ;
(T11 ) e  K  e ;
T1e  a  exp( / T );
Gd-doped Bi4Ge3O12
Nd-doped Bi4Ge3O12
meV
25
20
5
Δ
0
Hˆ CEF  B20O20  B40O40  B44O44  B60O60  B64O64
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.
Bi4Ge3O12
209Bi
I = 9/2 H = 0
m
±9/2
ν4
±7/2
ν3
±5/2
±3/2
±1/2
ν2
ν1
eQqzz

2
ˆ
HQ 
[3I z  I (I 1)  (I2  I 2 )]
4I (2I 1)
2