785
Russian Physics Journal, Vol. 52, No. 8, 2009
INVESTIGATION OF THE Mn-DOPED COMPOUND CuGaTe
2
BY
63
Cu AND
69
Ga NUCLEAR MAGNETIC RESONANCE TECHNIQUES
V. L. Matukhin,
1
V. L. Ermakov,
1
O. I. Gnezdilov,
2
UDC 621.315.592
E. V. Shmidt,
1
A. N. Safonov,
1
T. G. Aminov,
3
and G. G. Shabunina
3
The synthesized base compound CuGaTe
2
and the Mn-doped compounds Cu
0.97
Ga
0.97
Mn
0.06
Te
2
and
Cu
0.93
Ga
0.93
Mn
0.14
Te
2
have been investigated by using
63
Cu and
69
Ga NMR spectroscopy. The NMR spectra
obtained testify to substantial structural distortions near the cationic positions in the crystal lattice of Mn-
doped samples. The constants of quadrupole coupling between
63
Cu and
69
Ga nuclei in the compounds
investigated have been estimated.
Keywords: Spintronics, nuclear magnetic resonance, chalcopyrite semiconductors, doping.
INTRODUCTION
Compounds having the crystal structure of chalcopyrite doped with Mn are candidates for using in spintronic
devices owing to their rather high temperatures of magnetic ordering and adaptability to manufacture in the form of
high-quality single crystals and films [1]. It is well known that the materials that are suppliers of spin-polarized
electrons should meet the requirement of ferromagnetism at temperatures higher than room temperature combined with
the conductivity of semiconductors. First investigations on the creation of spintronic materials were associated with
type А
III
В
V
{Mn} diluted magnetic semiconductors. The next step was the production of high-temperature ferromagnetic
semiconductors of the А
II
В
IV
C
V
2
{Mn} type. Semiconductor compounds of the A
I
B
III
C
VI
2
type, having the structure of
chalcopyrite, also meet these requirements. They show high mobility of charging carriers. The transition element (Mn,
Fe, etc.) atoms take structural positions in anionic and cationic sublattices of these compounds thereby changing the
band structure, and this can provide the transition of the material into a ferromagnetic state with a rather high Curie
temperature and with the basic semiconductor properties preserved.
The goal of this work was to investigate solid solutions of CuGaTe
2
{Mn} with double substitution in cationic
sublattices by using
63
Cu and
69
Ga nuclear magnetic resonance (NMR). Previous investigations of chalcopyrite
compounds by using
63
Cu,
115
In, and
69
Ga NMR made it possible to obtain valuable data on the structural and dynamic
properties of these compounds, including the characteristics of nuclear quadrupole interactions and the coefficient of
diffusion of Cu(I) at high temperatures [2–6]. At the same time, it should be noted that of all the family of
semiconductor compounds having the crystal structure of chalcopyrite, tellurides are rather poorly understood compared
to selenides and sulfides.
The compound CuGaTe
2
is a diamagnetic, and its physical properties have been only recently determined on
the single-crystal samples grown up by the Bridgeman method (sample I) and by the tellurization method (sample II)
[7]. All the crystals produced possessed p-type conductivity, which retained on annealings in vacuum or in gallium
vapor. The reason for this seems to be the high concentration of intrinsic defects resulting from the initial deviation of
the compound composition from stoichometry. The concentration of holes in sample I decreased with decreasing
temperature, indicating that the mechanism of conductivity was related to the thermal activation of charge carriers from
1
Kazan State Power Engineering University, Kazan, Russia;
2
E. K. Zavosky Kazan Physicotechnical Institute
of the Kazan Science Center of the Russian Academy of Sciences, Kazan, Russia;
3
N. S. Kurnakov Institute of General
and Inorganic Chemistry of the Russian Academy of Sciences, Moscow, Russia, e-mail: alx_rus@mail.ru. Translated
from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 16–19, August, 2009. Original article submitted
March 16, 2009.
1064-8887/09/5208-0785 ©2009 Springer Science+Business Media, Inc.