Related Experiment Video
Updated: Jun 19, 2026
08:00
Chemical Synthesis of Porous Barium Titanate Thin Film and Thermal Stabilization of Ferroelectric Phase by Porosity-Induced Strain
Published on: March 27, 2018
Magnetic-field-induced polarization flop in multiferroic TmMn2O5
M Fukunaga1, Y Sakamoto, H Kimura
1Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan. fukunaga@tagen.tohoku.ac.jp
Physical Review Letters
|October 2, 2009
Summary
Researchers observed a reversible electric polarization flop in multiferroic TmMn2O5 below 5 K using a magnetic field. This magnetic-field-induced transition reveals new insights into multiferroic materials and their magnetic phase transitions.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Magnetism
Background:
- Multiferroic materials exhibit multiple ferroic orders, such as ferroelectricity and ferromagnetism.
- Rare-earth (R) manganites (RMn2O5) are a class of multiferroic materials with complex magnetic structures.
- Understanding the interplay between magnetic fields and electric polarization is crucial for novel device applications.
Purpose of the Study:
- To investigate the effect of an external magnetic field on the electric polarization of multiferroic TmMn2O5.
- To characterize the magnetic phase transitions associated with the observed polarization changes.
- To elucidate the microscopic mechanisms driving the polarization flop in this rare-earth compound.
Main Methods:
- Applied a magnetic field of approximately 0.5 T along the c axis to TmMn2O5 single crystals below 5 K.
- Utilized polarized neutron diffraction to probe the magnetic structure and spin chirality.
- Measured electric polarization changes in response to the applied magnetic field.
Main Results:
- Discovered a reversible electric polarization flop from the a axis (P(a)) to the b axis (P(b)) below 5 K under a c-axis magnetic field.
- Identified this flop as a magnetic-field-induced phase transition between two incommensurate magnetic (ICM) phases.
- Observed the disappearance of spin chirality in the bc plane in the P(a) phase, indicating a change in magnetic ordering.
Conclusions:
- The study presents the first example of such a polarization flop in rare-earth RMn2O5 compounds.
- The polarization in the ICM phases of TmMn2O5 is induced by an S(i) x S(j)-type interaction.
- This finding deepens the understanding of magnetoelectric coupling mechanisms in multiferroics.
Related Concept Videos
01:31Ferromagnetism
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...
01:30Paramagnetism
Paramagnets are materials with unpaired electrons that possess a finite magnetic moment. In the absence of a magnetic field, these moments are randomly oriented, and thus the net moment is zero. Under an external field, a torque acting on the moments tends to align them along the field's direction. However, the random thermal motion of electrons produces a torque opposite to the external field and tries to disorient the moments. These two competing effects align only a few moments along the...
01:27Magnetic Fields
A moving charge or a current creates a magnetic field in the surrounding space, in addition to its electric field. The magnetic field exerts a force on any other moving charge or current that is present in the field. Like an electric field, the magnetic field is also a vector field. At any position, the direction of the magnetic field is defined as the direction in which the north pole of a compass needle points.
A magnetic field is defined by the force that a charged particle experiences...
A magnetic field is defined by the force that a charged particle experiences...
01:23Magnetic Field due to Moving Charges
A stationary charge creates and interacts with the electric field, while a moving charge creates a magnetic field.
Consider a point charge moving with a constant velocity. Like the electric field, the magnetic field at any point is directly proportional to the magnitude of the charge and inversely proportional to the square of the distance between the source point and the field point. However, unlike the electric field, the magnetic field is always perpendicular to the plane containing the line...
Consider a point charge moving with a constant velocity. Like the electric field, the magnetic field at any point is directly proportional to the magnitude of the charge and inversely proportional to the square of the distance between the source point and the field point. However, unlike the electric field, the magnetic field is always perpendicular to the plane containing the line...
01:26Diamagnetism
Materials consisting of paired electrons have zero net magnetic moments. However, when these materials are placed under an external magnetic field, the moments opposite to the field are induced. Such materials are called diamagnets. Diamagnetism is the response of the diamagnets when placed in an external magnetic field.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.
01:31Magnetic Susceptibility and Permeability
In linear magnetic materials, like paramagnets and diamagnets, magnetization is proportional to the magnetic field intensity. The constant of proportionality, a dimensionless number, is called magnetic susceptibility. The value of the susceptibility depends on the type of material.
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...