  We investigated a possible use of the magnonic interferometric switches in
multi-valued logic circuits. The switch is a three-terminal device consisting
of two spin channels where input, control, and output signals are spin waves.
Signal modulation is achieved via the interference between the source and gate
spin waves. We report experimental data on a micrometer scale prototype based
on Y3Fe2(FeO4)3 structure. The output characteristics are measured at different
angles of the bias magnetic field. The On/Off ratio of the prototype exceeds 36
dB at room temperature. Experimental data is complemented by the theoretical
analysis and the results of micro magnetic simulations showing spin wave
propagation in a micrometer size magnetic junction. We also present the results
of numerical modeling illustrating the operation of a nanometer-size switch
consisting of just 20 spins in the source-drain channel. The utilization of
spin wave interference as a switching mechanism makes it possible to build
nanometer-scale logic gates, and minimize energy per operation, which is
limited only by the noise margin. The utilization of phase in addition to
amplitude for information encoding offers an innovative route towards
multi-state logic circuits. We describe possible implementation of the
three-value logic circuits based on the magnonic interferometric switches. The
advantages and shortcomings inherent in interferometric switches are also
discussed.
