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Magnetic properties of dislocations are attributed to unpaired electrons in their cores (dangling bonds [1] ). The unpaired electrons give rise to an electron paramagnetic resonance (EPR) signal [2,3] which can manifest itself as a spin-dependent current flow due to spin-dependent recombination (SDR) of the free carriers. [4,5] Much higher sensitivity of the SDR signal as compared with conventional EPR allows reduction of the frequency from the microwave range (usually applied for EPR) to a solenoid range [6,7] which allows use of various frequencies instead of only resonator frequency. A specific condition appears when the frequency is reduced to the VHF and HF range: the resonant value of the constant magnetic field and the amplitude of the alternating field are of the same order of magnitude (Fig. 1). This presumes the time constants contributing to the total SDR signal: spin-flip time, the field period and time constants related to the respective defect-zone transitions are comparable. The associated resonances from conduction electrons, defect holes and valence band holes would distort the resultant SDR resonance. [8,9] We present a study of the overall SDR peak position and amplitude at low frequencies as a function of alternating magnetic field. Thus, spin-dependent current changes follow the recombination rate.The sample (cut from an n-type Si wafer deformed nonuniformly to get a p±n structure as described in refs. 10 and 11 with a dislocation density r»10 8 cm ±2 ) was mounted in a flow cryostat under the crossed fields at 10 C and a 10 V forward bias was distributed between the high resistant p-base and the p±n junction. The frequency of the electromagnetic field was 3.5, 7 and 14 MHz and the amplitude was modulated with rectangular pulses (field on and off) to register the spin dependent additive with lock-in amplifier at the modulation frequency of 0.57 kHz. The SDR signal was registered as the current change at the constant voltage and various magnitudes of the alternating field from 0.5±1.2 Oe. A time constant was determined from SDR amplitude versus the modulation frequency dependencies within the 0.57±30 kHz range at various temperatures. The recombination mechanism of the current flow is supposed to prevail: the voltage drops generally over the base length.We used the model based on the Kaplan-Solomon-Mott (KSM) mechanism of the pair SDR. The basic concept of KSM model states that the recombination proceeds through the pair of paramagnetic states. The quantum mechanical theory for this mechanism is based on the Hamiltonian in its simplest form, which includes Zeeman terms only: [12] H À l B =2 h g I d I g II d II À Á H (1) g I,II are g-factors, r I,II are the Pauli spin matrices, subscripts I, II numerate the electrons belonging to a given pair, H is the magnetic field vector. This theory yields value of the SDR R s (H 0 , h~, s s , r, d, g) for the paired states as a function of H 0 ,h~± value of constant and amplitude of alternating magnetic fields; s s ± time constant of the spin-flip; g,d ± r...

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