EleTRnonIcally coNtrolled YIG nano-waveguiDe as mAgnon Delay line – TRINIDAD

During the first 6 months, the consortium has developped two techniques of growth of ultra thin films of YIG of the highest quality: pulsed laser deposition or liquid phase epitaxy.

The first results will be described in the report at T0+12.

RAS

RAS

The innovative objective of the TRINIDAD project is to extend to the microwave frequency range the concept of doped transmission used by optical telecommunication. A first aim is to develop within a 24 months period a loss-compensated spin-wave propagation medium. A second aim is to pattern this medium into a micron-size wave guide in order to achieve an analog delay line of unprecedented quality and integrable into the future electronics. The core idea of TRINIDAD is to join a magnetic insulator and a normal metal. In such a double-layered structure the magnetic insulator – Yttrium-Iron Garnet (YIG) – provides a low-loss propagation medium where an input microwave electromagnetic signal is converted into a slowly propagating spin-wave. A first key property of the targeted device is the use of ultra-thin films of YIG in order to reduce the group velocity of the spin-wave below 10m/s. A second key property is that intrinsic losses of the traveling spin-wave are partially or even fully compensated allowing the delay time to be increased beyond the natural spin-wave decay, which presently is a key issue that limits this technology. The oscillatory signal will be amplified by an injected flow of angular momentum (or pure spin current) from an out-of-equilibrium spin accumulation layer produced by the electrons moving in an adjacent metallic layer. The spin current will be created by the spin-Hall effect (requires strong spin-orbit metals or alloys: e.g. Pt, Ta or CuIr and AuW). The net result of the spin current will be to amplify (or to reduce, depending on the sign of the applied current) the propagating signal by the process of stimulated emission at the metal/insulator interface. Delays of few microseconds could then be potentially achieved over micrometer distances. In the future, such delay line could be used as the elementary building block for other high performance microwave devices such as an ultra-low phase noise oscillator or a voltage controlled tunable filter. Target applications lie in radar and telecommunication technology, which are looking for electronically tuned ultra-narrow band, non-reciprocal devices, combining both high-agility and ultra-narrow selectivity.