The mechanism explaining the key role of AFM correlations in formation of the heavy fermion state is offered. It is shown that in the case of (T* - TN)/TN ≪ 1, the critical spin fluctuations transform the mean-field second-order transition to RVB state into the crossover from high-temperature paramagnetic behavior of localized spins to strongly correlated spin liquid with quasi itinerant character of susceptibility. Thus the spin-liquid state by its origin is close to magnetic instability, so either short-range or long-range AFM order should arise at low T.
- Magnetic instability
- Spin liquid