Epitaxial MnP thin films: epitaxial growth, magnetic and electrical properties

Article abstract of DOI:10.1016/j.jmmm.2006.01.195

We have grown 500 ? MnP on undoped GaAs(1 0 0) substrate using solid-source molecular beam epitaxy. In order to characterize the crystal structure of MnP, we performed in-situ reflection high energy electron diffraction and θ-2θ XRD X-ray diffraction studies. From the measurements of superconducting quantum interference device, Quantum Design, MnP thin film shows ferromagnetic ordering at around 291.5 K. It shows a metallic resistivity in MnP thin film.

Full text of DOI:10.1016/j.jmmm.2006.01.195

ARTICLE IN PRESS
Journal of Magnetism and Magnetic Materials 304 (2006) e112–e114
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Epitaxial MnP thin films: epitaxial growth, magnetic and
electrical properties
a
Jeongyong Choi , Sungyoul Choi , M.H. Sohn , Hyoyeol Park , Yongsup Park ,
a
b
c
d
d
Hyun-Min Park , S.C. Hong , Sunglae Cho
a
a,e,Ã
a
Department of Physics, University of Ulsan, San 29, Muger 2-dong, Ulsan, 680-749, South Korea
b
Korea Electrotechnology Research Institute, 28-1, Seongju-dong, Changwon, Kyongnam, 641-120, South Korea
c
Department of Semiconductor Application, Ulsan College, Ulsan, 680-749, South Korea
d
Korea Research Institute of Standards and Science, Yuseong Daejeon, 305-600, South Korea
e
Nanodevice Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea
Available online 3 March 2006
Abstract
˚
We have grown 500 A MnP on undoped GaAs(1 0 0) substrate using solid-source molecular beam epitaxy. In order to characterize the
crystal structure of MnP, we performed in-situ reflection high energy electron diffraction and y–2y XRD X-ray diffraction studies. From
the measurements of superconducting quantum interference device, Quantum Design, MnP thin film shows ferromagnetic ordering at
around 291.5 K. It shows a metallic resistivity in MnP thin film.
r 2006 Elsevier B.V. All rights reserved.
PACS: 75.30.Kz; 75.70.ꢀi; 75.70.Ak
Keywords: MnP thin film; Lifshitz; MBE (molecular beam epitaxy)
1
. Introduction
crystals of MnP which was grown by the Bridgman method
have been used for physical property study [1,5–7].
In this article, we report on the epitaxial growth of MnP
thin films using solid source MBE (molecular beam
epitaxy) and its magnetic and electrical properties.
For the past many decades, MnP has been widely studied
because of its unique magnetic properties. It is known that
a single crystal of MnP, which has a strong magnetic
anisotropy, has helicoidal magnetic ordering below 47 K
and ferromagnetic (FM) ordering between 47 K and
T ¼ 291.5 K [1,2]. Furthermore, MnP has the Lifshitz
C
2
. Experiment
point where paramagnetic, ferromagnetic, and helicoidal
phases meet [3]. The Lifshitz point which has various
magnetic properties has been extensively studied [4].
The crystal structure of MnP is orthorhombic with
We have grown MnP thin film directly on semi-
insulating GaAs(1 0 0) substrate by MBE. Standard and
cracking effusion cells are used for Mn and P evaporations,
respectively. The growth was monitored with RHEED
˚
˚
lattice constants of a ¼ 5.916 A, b ¼ 5.260 A, and
˚
c ¼ 3.173 A, which is distorted from the NiAs-type
(reflection high energy electron diffraction). The growth
hexagonal crystal structure [1]. Up to now, the single
temperature of MnP was 500 1C and growth rate of Mn
˚
was 0.25 A/s under phosphorus ambience. We have grown
5
film was investigated using XRD (Model D/max-RC,
Rigaku Co., Tokyo, Japan) measurement.
Ã
Corresponding author. Department of Physics, University of Ulsan,
˚
00 A MnP thin film. The crystal structure of the grown
San 29, Muger 2-dong, Ulsan, 680-749, South Korea.
Tel.: +82 52 259 2322; fax: +82 52 259 1693.
E-mail address: slcho@mail.ulsan.ac.kr (S. Cho).
0304-8853/$ - see front matter r 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jmmm.2006.01.195

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J. Choi et al. / Journal of Magnetism and Magnetic Materials 304 (2006) e112–e114
e113
3
. Result and discussion
2
1
.0x10-4
Fig. 1 shows the logarithmically scaled y–2y XRD
pattern of MnP thin film grown on GaAs(1 0 0) substrate.
.0x10-4
0
50
100
150
200
250
300
Temperature (K)
Fig. 3. Temperature-dependent resistivity of MnP thin film.
GaAs substrate peaks and MnP peak are observed
without any other secondary peaks. The growth direction
of MnP on GaAs(1 0 0) substrate was (2 1 1).
Fig. 1. XRD pattern of MnP thin flim.
We have investigated the magnetic properties using
MPMS (magnetic property measurement system, Quantum
Design Inc.). MnP thin flim has FM ordering at around
300 K, as shown in Fig. 2. Interestingly, we have observed a
slight magnetization (M) change below 100 K and a FM
ordering below 47 K, which is similar with the reported
helicodal magnetic data below 47 K in bulk MnP [1,2]. The
change of transition temperature between FM and
helicoidal magnetic states from 47 to 100 K may be caused
by strain due to lattice mismatch between epitaxial MnP
film and GaAs substrate.
We have observed a metallic temperature dependent
resistivty data in MnP thin film with the negative
magneto-resistances, determined from PPMS (physical
property measurement system, Quantum Design Inc.),
as shown in Fig. 3. Electrical resistivity increases
with temperature. MnP has an electronic structure of
the metal.
4. Conclusion
We have grown the epitaxial MnP thin films on semi-
insulating GaAs(1 0 0) substrate using solid-source MBE
system. FM ordering was observed below about 300 K.
Helicoidal magnetic state was observed at low temperature.
MnP flim has a metallic resistivity data.
Acknowledgements
This work was supported by the SRC/ERC program of
MOST/KOSEF(grant #) R11-2000-071, KIST under vision
2
2
1, KOSEF Grant #R08-2003-000-10353-0, Brain Korea
1 Project in 2003, and KISTEP Grant # M1-0221-00-
Fig. 2. (a) M–T and (b) M–H curves of MnP thin flim.
0002.

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J. Choi et al. / Journal of Magnetism and Magnetic Materials 304 (2006) e112–e114
e114
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