Zerofield

Zerofield refers to a condition in which no external magnetic field is applied to a system under study. In practice, zerofield experiments strive to minimize ambient and stray magnetic fields to a level compatible with the measurement, often using magnetic shielding and active field compensation. The concept is central in many areas of physics, chemistry, and materials science where magnetic interactions are examined without Zeeman interactions from an external field.

In spectroscopy and solid-state physics, zerofield phenomena include zero-field splitting, where interactions within a system split degenerate spin states even in the absence of an applied field. This effect, described by spin Hamiltonians with anisotropic terms, is important for transition-metal complexes and defects in solids, such as nitrogen-vacancy centers in diamond. Zero-field NMR is another related area, where nuclear spin couplings like J-couplings drive the observed spectra without an external field, often relying on highly sensitive detectors to resolve small signals.

Applications and experiments commonly employ zerofield magnetometry, which measures magnetic properties without Zeeman shifts, providing access to intrinsic interactions such as hyperfine couplings. Achieving true zerofield conditions presents challenges due to residual fields, requiring specialized shielding, magnetic shielding materials, and active compensation.

Related terms include zero-field cooling in superconductors, and broader discussions of field-free or minimal-field techniques in various spectroscopic and magnetic sensing contexts. The term zerofield thus denotes a methodological or physical regime defined by the absence of an externally applied magnetic field.