1. Introduction 134
2. Sources of nonlinearity and optimum observing conditions 135
a) The equation system 135
b) Case of an anisotropic increment to the distribution function 136
c) The possibility of overheating of the electron system in metals 137
d) Conditions of observation 138
3. Nonlinear size effect 139
a) Qualitative discussion 139
b) Structure of direct-current spikes 140
c) Experimental observation of nonlinear size effect 140
4. "Current" states 142
a) General considerations 142
b) Calculation of rectified current 143
c) Experimental observation of "current" states in bismuth 145
d) Experiments on tin 147
5. Self-oscillations 149
a) Stability of "current" states 149
b) Growing magnetic-moment oscillations 150
c) Experimental observation of magnetic-moment self-oscillations 151
6. Surface impedance at high alternating-field amplitudes 151
a) Possibility of describing nonlinear effects in metals with the aid of the surface impedance 151
b) Experimental observation of surface impedance as a function of alternating-field amplitude 152
7. Conclusion 153
References 154