Spin Wave Excitation, Detection, and Utilization in the Organic-Based Magnet, V(TCNE) (TCNE = Tetracyanoethylene).

Spin waves, quantized as magnons, have low energy loss and magnetic damping, which are critical for devices based on spin-wave propagation needed for information processing devices. The organic-based magnet [V(TCNE) ; TCNE = tetracyanoethylene; x ≈ 2] has shown an extremely low magnetic damping comparable to, for example, yttrium iron garnet (YIG). The excitation, detection, and utilization of coherent and non-coherent spin waves on various modes in V(TCNE) is demonstrated and show that the angular momentum carried by microwave-excited coherent spin waves in a V(TCNE) film can be transferred into an adjacent Pt layer via spin pumping and detected using the inverse spin Hall effect.

Separation of Spin and Charge Transport in Pristine π-Conjugated Polymers.

We have experimentally tested whether spin-transport and charge-transport in pristine π-conjugated polymer films at room temperature occur via the same electronic processes. We have obtained the spin diffusion coefficient of several π-conjugated polymer films from the spin diffusion length measured by the technique of inverse spin Hall effect and the spin relaxation time measured by pulsed electrically detected magnetic resonance spectroscopy. The charge diffusion coefficient was obtained from the time-of-flight mobility measurements on the same films.

Spin current from sub-terahertz-generated antiferromagnetic magnons.

Spin dynamics in antiferromagnets has much shorter timescales than in ferromagnets, offering attractive properties for potential applications in ultrafast devices. However, spin-current generation via antiferromagnetic resonance and simultaneous electrical detection by the inverse spin Hall effect in heavy metals have not yet been explicitly demonstrated. Here we report sub-terahertz spin pumping in heterostructures of a uniaxial antiferromagnetic CrO crystal and a heavy metal (Pt or Ta in its β phase).

Surface-enhanced spin current to charge current conversion efficiency in CHNHPbBr-based devices.

Hybrid organic-inorganic perovskites have shown great promise for spintronic applications due to their large spin-orbit coupling induced by the Pb and halogen atoms. Particularly, the large observed surface-induced Rashba splitting in CHNHPbBr indicates efficient spin-current-to-charge-current (StC) conversion, which, however, has not been demonstrated yet. In this work, the StC conversion efficiency in ferromagnet/CHNHPbBr-based devices is studied using the pulsed spin-pumping technique measured by the inverse spin Hall effect.

Field-tunable quantum disordered ground state in the triangular-lattice antiferromagnet NaYbO.

Antiferromagnetically coupled spins on an isotropic triangular lattice are the paradigm of frustrated quantum magnetism, but structurally ideal realizations are rare. Here, we investigate NaYbO, which hosts an ideal triangular lattice of effective moments with no inherent site disorder. No signatures of conventional magnetic order appear down to 50 mK, strongly suggesting a quantum spin liquid ground state.

Organic-based magnon spintronics.

Magnonics concepts utilize spin-wave quanta (magnons) for information transmission, processing and storage. To convert information carried by magnons into an electric signal promises compatibility of magnonic devices with conventional electronic devices, that is, magnon spintronics . Magnons in inorganic materials have been studied widely with respect to their generation, transport and detection .

Hexacyanobutadienide-Based Frustrated and Weak Ferrimagnets: M(HCBD)2·zCH2Cl2 (M = V, Fe).

Hexacyanobutadiene (HCBD) and M(CO)x (M = V, x = 6; Fe, x = 5) react in CH2Cl2 to form new organic-based magnets of M[HCBD]2·z(CH2Cl2) composition. Analysis of the IR spectrum [M = V: ν(CN) 2193 and 2116 cm(-1) (fwhh ∼400 cm(-1)); Fe: 2196 and 2145 (fwhh ∼150 cm(-1))] suggests that HCBD is reduced to the radical anion, [HCBD](•-), and the broadness suggests multiple and variable nitriles sites are coordinated to the V(II), leading to a complex mixture of magnetic couplings and behaviors that deviate from paramagnetic behavior below ∼150 K, and a frustrated magnet with Tc ≈ 9 K is observed for V[HCBD]2, the first cyanocarbon-based frustrated magnet. Fe[HCBD]2 behaves as a weak ferromagnet (canted antiferromagnet) with some spin glass behavior with a 10 K Tc.

Characterization of Tetracyanopyridine (TCNPy)-Based Magnets: V[TCNPy]2 ⋅z (CH2 Cl2 ) (Tc =111 K) and V[TCNPy]3 ⋅z (CH2 Cl2 ) (Tc =90 K).

The reaction of 2,3,5,6-tetracyanopyridine (TCNPy) with V(CO)6 in CH2 Cl2 forms new organic-based magnets of V[TCNPy]x ⋅z (CH2 Cl2 ) (x=2, 3) composition. Analysis of the IR spectra suggests that the TCNPy is reduced and coordinated to V(II) sites through the nitriles. V[TCNPy]x order as ferrimagnets with 111 and 90 K Tc values for V[TCNPy]2 and V[TCNPy]3 , respectively.

The Tetracyanopyridinide Dimer Dianion, σ-[TCNPy]2 (2.).

The reaction of 2,3,5,6-tetracyanopyridine (TCNPy) and Cr(C6 H6 )2 forms diamagnetic σ-[TCNPy]2 (2-) possessing a 1.572(3) Å intrafragment sp(3) -sp(3) bond. This is in contrast to the structurally related 1,2,4,5-tetracyanobenzene and 1,2,4,5-tetracyanopyrazine that form π-dimer dianions possessing long, multicenter bonds.

Inverse spin Hall effect from pulsed spin current in organic semiconductors with tunable spin-orbit coupling.

Exploration of spin currents in organic semiconductors (OSECs) induced by resonant microwave absorption in ferromagnetic substrates is appealing for potential spintronics applications. Owing to the inherently weak spin-orbit coupling (SOC) of OSECs, their inverse spin Hall effect (ISHE) response is very subtle; limited by the microwave power applicable under continuous-wave (cw) excitation. Here we introduce a novel approach for generating significant ISHE signals in OSECs using pulsed ferromagnetic resonance, where the ISHE is two to three orders of magnitude larger compared to cw excitation.