Terahertz Spintronic Emitter with Arbitrarily Controllable Linear Polarization Properties not Needing a Rotating Magnetic Bias

Spintronic THz emitters are new intensively studied sources of THz radiation with high potential in broadband THz time-domain spectroscopy. We present a novel architecture for a spintronic emitter based on a ferromagnetic heterostructure with an induced in-plane magnetic anisotropy. This new approach allows to generate an arbitrary linear THz polarization taking advantage of the coherent Stoner-Wohlfarth rotation of the magnetic heterostructure. As a result the linear THz polarization state can be tuned without rotating the applied magnetic field. Combined with the huge bandwidth of the emitter, this may lead to high impact for terahertz ellipsometry and polarimetry.