= Critical exponent
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A critical exponent specifies a leading power-law singularity near a <continuous phase transition>. For dimensionless distance $t$ from the critical temperature, examples are $\xi\sim|t|^{-\nu}$ for the <correlation length> and $\chi\sim|t|^{-\gamma}$ for the <magnetic susceptibility>. The exponents describe how observables change, while nonuniversal amplitudes set their sizes.
Experimentally, estimating an exponent requires a range where critical scaling dominates over microscopic effects yet remains outside finite-size or instrumental rounding. A logarithmic slope over a short interval can be an effective exponent rather than the limiting one. Systems in one <universality class> share the limiting exponents under the stated assumptions. <Scaling relations for critical exponents> connect some exponents, so they are not all independent parameters.
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