Photon Factory Activity Report 2005 #23 Part B (2006)
Materials Science

16A1/2005S2-003

Measurement System of X-ray Diffraction in Strong Magnetic Fields
T. ARIMA1*, D. OKUYAMA2, T. MATSUMURA2, Y. MURAKAMI2,T. KAKIUCHI3, H. SAGAYAMA1,3, H. SAWA3
1
IMRAM, Tohoku Univ., Sendai 980-8577, Japan
2
Dept. Phys., Tohoku Univ., Sendai 980-8578, Japan
3
KEK-PF, Tsukuba, Ibaraki 305-0801, Japan
Introduction
Magnetic-field-induced phenomena such as colossal
magnetoresistance (CMR) or giant magnetoelectriceffects (GME) have recently stimulated interest of many
scientists.[1,2] These phenomena are closely related tosome order-disorder transition in spin, orbital, and charge
degrees of freedom. Some new methods to probe theordering were developed at Photon Factory. For example,
Murakami et al. have first pointed out that x-ray
scattering through anomalous tensor susceptibility (ATS)in the CMR-related manganite compounds is attributed toorbital ordering.[3]In 2005, we fabricated a measurement system ofsynchrotron x-ray diffraction in magnetic fields to extend
the activity on correlated electron systems at PhotonFactory.
Specification of the System
A cryostat equipped with an 8-Tesla superconducting
magnet (Cryomagnetics, Inc.) is mounted on a multicircle diffractometer (Huber Co. Ltd.) with a horizontal
scattering plane. Magnetic fields are applied vertical, i.e.,
perpendicular to the scattering vector.
Beryllium
windows are coordinated on the cryostat as shown in Fig.
1. One can collect scattering data with an angle less than
120 degree can be measured. Temperature of a sample
mounted on a top-loaded rod can be controlled between
1.5 and 300 K. We found that scintillation counters are
sensitive to high magnetic fields. Therefore we use asilicon PIN x-ray detector (Amptek Inc.) to avoid themagnetic-field effect.

In the present system, orientation of single crystalline
sample should be prior to the experiment because thecryostat can be tilt by less than 3 degrees. We now design
a new sample rod geared with a sample rotator.
Ongoing Studies
We start the following studies by using themeasurement system. The results will be published innear future.
Magnetoelectric Perovskite Manganites
TbMnO3 undergoes a transition from ferroelectric toparaelectric phase with the application of magnetic fieldalong the a axis. We have found that superlatticereflections with a modulation vector (0 Q 0) suddenly
disappear upon the transition. This result implies that thetransition should result from the change ofantiferromagnetic spin arrangement from the long-period
type to the layered type.
With a magnetic field along the b axis, the ferroelectric
polarization in TbMnO3 flops by 90 degrees,
accompanied by the incommensurate-commensuratetransition of antiferromagnetism and superlatticemagnetostriction. In contrast, almost no change withpolarization flop was found in superlattice modulation
vector in the cases of DyMnO3 and (Eu,Y)MnO3.
Magnetoresistive Perovskite Manganite Films
Change in structure of Nd0.5Sr0.5MnO3 film on SrTiO3(110) substrate upon the ferromagnetic transition wasinvestigated. With warming the sample in lower magnetic
fields than 3 T, a change in lattice constants is observed atabout 10 K lower than the metal-insulator transition
temperature. The intermediate phase might be the socalled A-type layered antiferromagnetic phase. In higher
magnetic fields, the lattice constants change
simultaneously with the metal-insulator transition.
References[1] Y. Tokura et al., Rep. Prog. Phys. 69, 797 (2006).
[2] M.Fiebig, J. Phys. D: Appl. Phys. 38, R123 (2005).
[3] Y. Murakami et al., Phys. Rev. Lett. 80, 1932 (1997);
ibid 81, 582 (1998).
* arima@tagen.tohoku.ac.jp

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