We uncover the fine structure of a silicon vacancy in isotopically purified silicon carbide (4H-28 SiC) and reveal not yet considered terms in the spin Hamiltonian, originated from the trigonal pyramidal symmetry of this spin-3/2 color center. These terms give rise to additional spin transitions, which would be otherwise forbidden, and lead to a level anticrossing in an external magnetic field. We observe a sharp variation of the photoluminescence intensity in the vicinity of this level anticrossing, which can be used for a purely all-optical sensing of the magnetic field. We achieve dc magnetic field sensitivity better than 100 nT/ √ Hz within a volume of 3 × 10 −7 mm 3 at room temperature and demonstrate that this contactless method is robust at high temperatures up to at least 500 K. As our approach does not require application of radiofrequency fields, it is scalable to much larger volumes. For an optimized light-trapping waveguide of 3 mm 3 the projection noise limit is below 100 fT/ √ Hz.

We discovered uniaxial oriented centers in silicon carbide having unusual performance. Here we demonstrate that the family of silicon-vacancy related centers with S= 3/2 in rhombic 15R-SiC crystalline matrix possess unique characteristics such as optical spin alignment existing at temperatures up to 250• C. Thus the concept of optically addressable silicon vacancy related centers with half integer ground spin state is extended to the wide class of SiC rhombic polytypes. The structure of these centers, which is a fundamental problem for quantum applications, has been established using high frequency ENDOR. It has been shown that a family of silicon-vacancy related centers is a negatively charged silicon vacancy in the paramagnetic state with the spin S= 3/2, VSi − , perturbed by neutral carbon vacancy in non-paramagnetic state, VC 0 , having no covalent bond with the silicon vacancy and located adjacently to the silicon vacancy on the c crystal axis.Spin centers in Silicon Carbide (SiC) have recently been put forward as favorable candidates for a new generation quantum spintronics and sensorics, as well as quantum information processing because of the unique properties of their electron spins which can be optically polarized and read out [1][2][3][4][5][6][7][8][9][10][11]. Particularly the optical control of the single defect spin in SiC has been realized at room temperature for the first time on the well studied silicon vacancy-related center with ground spin state S= 3/2 in 4H-SiC [10]. The centers of the same origin persist also in 6H-SiC polytype and were proposed for use in quantum magnetometry [6] and room temperature operated MASERs [8]. Thus the family of the V Si related centers can be considered to form the basis of the SiC-based quantum sensors and quantum spintronics. The first solid state system on which optical detection and manipulation of the single spin has been shown is the negatively charged nitrogen-vacancy (NV − ) center in diamond. There are two main reasons why successful realization of single spin control in this system was possible. First, the NV − centers possess high optically detected magnetic resonance (ODMR) contrast and their spin alignment persists at elevated temperatures [12], thusthe polarized spin state can be readout with high fidelity even on the single spin [13]. Second, the precise atomic structure of the center has been elucidated [14][15]. This gave rise to the precise technology of NV's production in predetermined topology and concentrations [16], [17], allowing one to organize precise control of the NV's electron spin interactions with the environment. This permits to develop NV − based quantum registers [18], [19] and quantum sensors [20], [21].Therefore for the successful development of the SiC two major issues have to be addressed. On the one hand spin centers with high breakdown characteristics and high ODMR contrast must be explored, on the other hand the proper model for these spin centers must be established. We focused our efforts on these two tasks and present...

The cover picture shows a microfl uidic channel and the magnetochromatic microspheres it generates. From a single-synthesis environment, structural-colored microspheres are synthesized by combining an optofl uidic approach with a magnetic property tuning method. The main image features the dynamic color tuning capability of the method; differently colored microspheres are generated in a single microfl uidic channel, and color can be changed in real-time during the synthesis process. The microspheres are produced with controlled and heterogeneous optical properties. They comprise 1D chain arrangements of magnetic nanoparticles, as shown by the microsphere in the foreground. The magnetic nanoparticles enable the microspheres to have the unique structural color. Orientation-dependent color diffraction of the magnetochromatic microspheres can be utilized to form structural color patterns using a patterned magnet. For more information, please read the Communication "Real-Time Optofl uidic Synthesis of Magnetochromatic Microspheres for Reversible Structural Color Patterning" by S. Kwon and coworkers, beginning on page 1163.The frontispiece features the multistrata nanoparticle-a single-core, fi ve-layered nanostructure. It combines tunable, dual-peak, UV-vis-NIR spectrum extinction characteristics; trimodal imaging contrast; a simple synthesis; and facile surface modifi cation capabilities into a single <60-nm-diameter, multifunctional nanosphere that seeks to relieve current methodological limitations by coupling diagnostics and therapeutics into one single theranostic tool. The image shows a model of the interior, multilayered, metallodielectric structure, including a schematic of the fabrication protocol. For more information, please read the Communication "The Multistrata

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