Synopsis: Noisy spins

Ever present fluctuations in semiconductors can be utilized as a demolition-free spectroscopic probe to study ultrafast spin dynamics.
Synopsis figure
Illustration: Courtesy of G. M. Müller et al.

Though they are often disruptive, statistically ever-present fluctuations can at times provide valuable information about the dynamics of a physical system. For example, a multitude of independently precessing spins in a semiconducting material gives rise to spin fluctuations that can be probed via spin noise spectroscopy. This method, previously used for gaseous atoms, was introduced to study semiconductors in 2005, where it offers the dual benefits of low heating and smaller perturbative effects on the probed spin dynamics. These advantages, however, were to some extent outweighed by the inability of spin noise spectroscopy to probe higher frequencies.

In a Rapid Communication published in Physical Review B, Georg M. Müller, Michael Römer, Jens Hübner, and Michael Oestreich from Leibniz Universität Hannover, Germany, use a pulsed Ti: Sapphire laser (instead of a continuous-wave laser) to effectively slow down spin fluctuations as though they were viewed under a strobe light, and perform spin noise spectroscopy at ultrahigh frequencies up to several GHz. This extension to higher frequencies, without any loss of sensitivity, may reshape spin noise spectroscopy into a tool that studies intriguing phenomena such as Bose-Einstein condensation of magnons and reaction kinetics in chemical physics. More immediately, this development enables the authors to explore in detail the spin dynamics in n-doped GaAs—in many respects the quintessential spintronics material. – Sami Mitra


Announcements

More Announcements »

Subject Areas

Semiconductor PhysicsSpintronics

Previous Synopsis

Particles and Fields

Calculations for complex nuclei

Read More »

Next Synopsis

Fluid Dynamics

Sticky water

Read More »

Related Articles

Viewpoint: Crystal Vibrations Invert Quantum Dot Exciton
Semiconductor Physics

Viewpoint: Crystal Vibrations Invert Quantum Dot Exciton

Phonons assist in creating an excitation-dominated state, or population inversion, in a single quantum dot—an effect that could be used to realize single-photon sources. Read More »

Synopsis: Controlling Magnetism by Electricity
Magnetism

Synopsis: Controlling Magnetism by Electricity

Small voltages can control the magnetic properties of thin films at room temperature. Read More »

Viewpoint: Diamond Spins Shining Bright
Quantum Information

Viewpoint: Diamond Spins Shining Bright

The spin on a silicon defect in diamond can be prepared in a coherent quantum state, a promising sign that it could encode information in a quantum internet. Read More »

More Articles