NMR spectrometers for magnetic materials

Description

Nuclear Magnetic Resonance (NMR) consists in resonance absorption of  phonons corresponding to the energy difference  between consecutive energy levels of nuclear spins  in magnetic field. In case of magnetically ordered solids the resonance takes place in an internal magnetic field, inherent to the magnetic state of the matter, and thus it can be used as a probe of local magnetic properties. The NMR spectrum represents  a distribution of the local internal magnetic fields in particular crystallographic position.

Specification

• 3 fully automated broadband spin echo spectrometers
• Frequency range of operation: 30-320 MHz, 300-1000 MHz, and 20-600 MHz
• Observed isotopes: ⁵⁹Co, ⁵⁷Fe, ⁵⁵Mn, ¹²¹Sb, ¹²³Sb and ⁹⁵Mo, ⁹⁷Mo, ⁷⁵As, ¹¹⁹Sn, ¹⁴³Nd, ¹⁴⁵Nd ¹⁴⁹Sm, ¹⁵³Eu ¹⁵⁵Gd, ¹⁸⁷Re
• specialized, custom made  software for data acquisition and analysis

Applications

Due to a strong relationship between a local magnetic field and local crystalographic environments the NMR technique provides a detailed information on crystallographic Short Range Order present in the sample. In this way NMR is complementary to other structural techniques such as  electron-microscopy, X-rays or EXAFS.  On the other hand the NMR experiment provides the information on spin density distribution and thus it complements  the  macroscopic magnetometry.  In addition, NMR experiment provides the  frequency dependent magnetic restoring field which can be related to a local magnetic stiffness, resulting from magnetocrystalline anisotropy, coercivity, etc.