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Torque On A Current Loop In A Magnetic Field

Torque On A Current Loop In A Magnetic Field

The most common application of magnetic force on current-carrying wires is in electric motors. These consist of loops of wire, which are placed between the magnets with a magnetic field. When current flows through the loops, the magnetic field applies torque, which causes the shaft to rotate, thus converting electrical energy to mechanical energy.
Consider a rectangular current-carrying loop containing N turns of wire, placed in a uniform magnetic field. The net force on a current-carrying loop...

Torque

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Magnetic Force On Current-Carrying Wires: Example

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In a magnetic field, moving charges encounter a force. If a wire contains these moving charges, i.e., if the wire is carrying a current, then a force acts on the wire as well. Consider a pair of flexible leads holding a wire that is 40 cm long and 10 g in weight in a horizontal position. The wire is placed in a constant magnetic field of 0.40 T, as shown in Figure 1(a). Determine the magnitude and direction of the current flowing in the wire needed to remove the tension in the supporting leads.

Magnetic Field due to Moving Charges

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Related Experiment Video

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Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope

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Spin-transfer torque generated by a topological insulator.

A R Mellnik¹, J S Lee², A Richardella²

¹Cornell University, Ithaca, New York 14853, USA.

|July 25, 2014

Summary

Topological insulators like bismuth selenide efficiently control magnetic materials using spin-transfer torque. This breakthrough could lead to advanced, low-power magnetic memory and logic devices.

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Magnetic Tweezers for the Measurement of Twist and Torque

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Published on: May 19, 2014

Area of Science:

Condensed Matter Physics
Materials Science
Spintronics

Background:

Magnetic devices offer non-volatile, high-density, high-speed, and durable memory and logic solutions.
Efficient current-driven magnetization manipulation is crucial for widespread adoption of magnetic technologies.
Spin-orbit interactions, via spin Hall or Rashba-Edelstein effects, are key mechanisms for current-driven torques.

Purpose of the Study:

To investigate the potential of topological insulators, specifically bismuth selenide (Bi2Se3), for efficient spin-orbit-induced torques.
To experimentally demonstrate current-driven spin-transfer torque from topological insulator surface states onto adjacent ferromagnetic layers.
To evaluate the efficiency of Bi2Se3 as a spin-orbit torque source for magnetic manipulation.

Main Methods:

Fabrication of thin films comprising a topological insulator (Bi2Se3) and a ferromagnet (permalloy, Ni81Fe19).
Electrical transport measurements at room temperature to detect current-induced magnetic effects.
Analysis of torque strength per unit charge current density.

Main Results:

Charge current in Bi2Se3 generated a strong spin-transfer torque on the adjacent Ni81Fe19 film.
The observed torque direction aligns with predictions from topological insulator surface states.
The torque efficiency in Bi2Se3 surpassed previously reported spin-transfer torque sources, even in films with bulk conduction.

Conclusions:

Topological insulators, such as Bi2Se3, are highly effective sources of spin-transfer torque.
This research demonstrates the feasibility of using topological insulators for efficient electrical manipulation of magnetic materials.
The findings suggest a promising pathway towards developing next-generation, low-power magnetic memory and logic devices operating at room temperature.