Magnetic-field- and pressure-induced quantum phases in complex materials
Minjung Kim1, Harini Barath, Xiaoqian Chen
1Department of Physics and Frederick Seitz Materials Research Laboratory University of Illinois, Urbana-Champaign Urbana, IL 61801, USA.
Advanced Materials (Deerfield Beach, Fla.)
|April 20, 2010
Summary
This report details Raman spectroscopy studies on complex materials like manganese perovskites and charge-density wave systems. Field and pressure tuning reveal diverse phases and microscopic changes in these strongly correlated materials.
Area of Science:
- Condensed matter physics
- Materials science
- Spectroscopy
Background:
- Raman spectroscopy is employed to investigate strongly correlated materials.
- Focus on charge-ordering manganese perovskites, multiferroic TbMnO(3), and charge-density wave (CDW) materials (1T-TiSe(2), Cu(x)TiSe(2)).
Discussion:
- Temperature, magnetic field, and pressure dependencies of Raman scattering are analyzed.
- These external stimuli are used to tune material properties and access different phases.
Key Insights:
- External fields (magnetic and pressure) effectively tune the properties of complex materials.
- Raman scattering elucidates microscopic changes associated with tunable behavior.
- Demonstrates the rich phase diagrams accessible in these materials.
Outlook:
- Further exploration of field- and pressure-induced phenomena in correlated electron systems.
- Application of these methods to discover novel quantum phases.
- Understanding the interplay between structure, magnetism, and electronic properties.
Related Concept Videos
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...
01:23Atomic Nuclei: Nuclear Relaxation Processes
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis. This...
01:24Potential Due to a Magnetized Object
Magnetic dipoles in magnetic materials are aligned when placed under an external magnetic field. For paramagnets and ferromagnets, dipole alignment occurs in the direction of the magnetic field. However, the dipoles align opposite to the field in the case of diamagnets. This state of magnetic polarization due to the external field is called magnetization. Magnetization is defined as the dipole moment per unit volume. It plays a similar role to polarization in electrostatics.
The vector...
The vector...
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...
01:19Magnetic Field Lines
The representation of magnetic fields by magnetic field lines is very useful in visualizing the strength and direction of the magnetic field. Each of the magnetic field lines forms a closed loop. The field lines emerge from the north pole (N), loop around to the south pole (S), and continue through the bar magnet back to the north pole.
Magnetic field lines follow several hard-and-fast rules:
Magnetic field lines follow several hard-and-fast rules: