Spin-polarized scanning tunneling microscopy

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The spin-polarized scanning tunneling microscopy ( English spin-polarized scanning tunneling microscopy , SP-STM ) is a modification of the scanning tunneling microscopy . It enables the observation and investigation of magnetism at the atomic level.

Measuring principle

In the simplest case, the sample to be examined is scanned with a tunnel tip at a distance of less than one nanometer , the tunnel tip being coated with a thin layer of a magnetic material. An electrical voltage between the sample and the tip creates a tunnel current . Without a magnetization effect, this current is strongly dependent on the electronic properties of the sample. If the tunnel tip is magnetized, electrons with a spin orientation that matches the magnetization of the tip are more likely to tunnel ( magnetic tunnel resistance ) than electrons with a reverse spin orientation. The area between the tip and the sample acts like a spin valve , i.e. an analyzer for the polarization of the electrons. The tunnel current reacts accordingly sensitively to changes in the magnetic properties of the sample.

application

Using spin-polarized scanning tunneling microscopy, detailed information about the magnetic properties of the sample surface and their correlation to the morphology of the sample surface can be obtained. Spin-polarized scanning tunneling microscopy enables the precise analysis of magnetic dynamic and static processes of magnetism, for example the properties of magnetic domains at the atomic level in ferromagnetic and antiferromagnetic systems or the influence of temperature and tunneling current on magnetic nanoparticles .

literature

  • Roland Wiesendanger: Spin mapping at the nanoscale and atomic scale . In: Reviews of Modern Physics . tape 81 , no. 4 , November 18, 2009, p. 1495-1550 , doi : 10.1103 / RevModPhys.81.1495 .