Related Experiment Video
Updated: Apr 27, 2026
06:24
High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
5.7K
Twist-bend nematic liquid crystals in high magnetic fields
P K Challa1, V Borshch2, O Parri3
1Department of Physics, Kent State University, Kent, Ohio 44242, USA.
Summary
Magneto-optic measurements reveal that magnetic fields can suppress the stripe texture in twist-bend nematic (Ntb) materials. A strong magnetic field also lowers the Ntb phase transition temperature, offering insights into this unique liquid crystal phase.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Physical Chemistry
Background:
- The twist-bend nematic (Ntb) phase is a unique liquid crystal state characterized by three-dimensional orientational anisotropy and long-range translational order.
- Ntb materials can exhibit spontaneous macroscopic stripe textures, impacting their optical properties.
Purpose of the Study:
- To investigate the influence of magnetic fields on the Ntb phase and its associated stripe texture.
- To elucidate the mechanism behind stripe formation and the magnetic field's effect on the N-Ntb phase transition.
Main Methods:
- Magneto-optic measurements were performed on two materials exhibiting the Ntb phase.
- Variable magnetic fields were applied to observe their effect on the stripe texture and phase transition temperature.
Main Results:
- A magnetic field was shown to persistently inhibit the formation of the optical stripe texture in Ntb materials.
- A 25T external magnetic field reduced the N-Ntb phase transition temperature by nearly 1°C.
- A quantitative mechanism for the magnetic field-induced shift in transition temperature was proposed.
Conclusions:
- Magnetic fields offer a method to control the stripe texture in Ntb phases.
- The findings support a Helfrich-Hurault-type mechanism for optical stripe formation.
- Understanding these magneto-optic effects is crucial for potential applications of Ntb materials.
Related Concept Videos
01:27Magnetic Fields
5.9K
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...
5.9K
01:05Atomic Nuclei: Magnetic Resonance
1.2K
The number of nuclear spins aligned in the lower energy state is slightly greater than those in the higher energy state. In the presence of an external magnetic field, as the spins precess at the Larmor frequency, the excess population results in a net magnetization oriented along the z axis. When a pulse or a short burst of radio waves at the Larmor frequency is applied along the x axis, the coupling of frequencies causes resonance and flips the nuclear spins of the excess population from the...
1.2K
01:23Atomic Nuclei: Nuclear Relaxation Processes
1.1K
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.
1.1K
01:23Magnetic Field due to Moving Charges
11.3K
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...
11.3K
01:03Atomic Nuclei: Nuclear Spin State Overview
1.9K
NMR-active nuclei have energy levels called 'spin states' that are associated with the orientations of their nuclear magnetic moments. In the absence of a magnetic field, the nuclear magnetic moments are randomly oriented, and the spin states are degenerate. When an external magnetic field is applied, the spin states have only 2 + 1 orientations available to them. A proton with = ½ has two available orientations. Similarly, for a quadrupolar nucleus with a nuclear spin value of one, the...
1.9K
00:59Atomic Nuclei: Nuclear Magnetic Moment
3.0K
All atomic nuclei are positively charged. When they have a nonzero spin, they behave like rotating charges. As a consequence of their charge and spin, these nuclei generate a magnetic field (B). This, in turn, gives rise to a magnetic moment (μ), which is randomly oriented in the absence of an external magnetic field. When an external magnetic field (B0) is applied, the magnetic moment vectors can align with the field or against it in 2 + 1 orientations. A hydrogen nucleus, which is just a...
3.0K