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Superfluidity and superconductivity are macroscopic manifestations of quantum mechanics, which have fascinated scientists since their discoveries roughly a century ago. Ever since the initial theories of such quantum fluids were formulated, there has been speculation as to the possibility of multi-component quantum order. A particularly simple multi-component condensate is built from particles occupying different quantum states, or bands, prior to condensation. The particles in one or both bands may undergo condensation, as seen for certain solids and anticipated for certain cold atom systems. For bulk solids, the different bands always order simultaneously, with conventional pairing characterized by complex order parameters describing the condensates in each band. Another type of condensate, notably occurring at room temperature, has been identified for magnons, the magnetic analogue of lattice vibrations, injected by microwaves into yttrium iron garnet. Here we show that magnon quantization for thin samples results in a new multi-band magnon condensate. We establish a phase diagram, as a function of microwave drive power and frequency relative to the magnon bands, revealing both single and multi-band condensation. The most stable multi-band condensate is found in a narrow regime favoured on account of a resonance in the scattering between two bands. Our discovery introduces a flexible non-equilibrium platform operating at room temperature for a well-characterised material, exploiting a Feshbach-like resonance, for examining multi-band phenomena. It points to qualitatively new ways to engineer and control condensates and superconducting states in multiband systems and potential devices containing multiple interacting condensates.

File formats are described in read_me.pdf files in the concerning folders. For plotting and data evaluation, Python 2.7 was used. Example scrips for plotting are provided.

File formats are described in read_me.pdf files in the concerning folders. For plotting and data evaluation, Python 2.7 was used. Example scrips for plotting are provided. &nbsp

Raw data associated to the manuscript “Nanoimaging of Ultrashort Magnon Emission by Ferromagnetic Grating Couplers at GHz Frequencies”, Nano Letters (2020), DOI: https://dx.doi.org/10.1021/acs.nanolett.0c02645 Information about file formats and measurement parameters are described in read_me.txt files in the specific folders. For plotting Python 3.7 was used, example scripts are provided. Paper abstract: On-chip signal processing at microwave frequencies is key for modern mobile communication. When one aims at small footprints, low power consumption, reprogrammable filters, and delay lines, magnons in low-damping ferrimagnets offer great promise. Ferromagnetic grating couplers have been reported to be specifically useful as microwave-to-magnon transducers. However, their interconversion efficiency is unknown and real-space measurements of the emitted magnon wavelengths have not yet been accomplished. Here, we image with subwavelength spatial resolution the magnon emission process into ferrimagnetic yttrium iron garnet (YIG) at frequencies up to 8 GHz. We evidence propagating magnons of a wavelength of 98.7 nm underneath the gratings, which enter the YIG without a phase jump. Counterintuitively, the magnons exhibit an even increased amplitude in YIG, which is unexpected and due to a further wavelength conversion process. Our results are of key importance for magnonic components, which efficiently control microwave signals on the nanoscale., We acknowledge the financial support by the Swiss National Science Foundation (SNSF), via grant numbers 163016 and 171003 (Sinergia project Nano-skyrmionics), and by the Federal Ministry of Education and Research of Germany in the framework of DynaMAX (project number 05K18EYA). Measurements were conducted at the Maxymus endstation at BESSY2, HZB, Berlin, Germany. The authors thank HZB for the allocation of synchrotron radiation beamtime.

Raw data associated to the manuscript "Plasma-enhanced atomic layer deposition of nickel nanotubes with low resistivity and coherent magnetization dynamics for 3D spintronics". Journal: ACS Appl. Mater. Interfaces (2020); doi: 10.1021/acsami.0c06879. For plotting and data evaluation Python 2.7, Excell and Origin 2008b were used. Extra information were provided in info.txt files. Funding by the German Science Foundation DFG via GR1640/5-2 in SPP1538 “Spin caloric transport” and SNF via grants 163016, BSCGI0 157705, and NCCR QSIT is gratefully acknowledged. Paper abstract: We report plasma-enhanced atomic layer deposition (ALD) to prepare conformal nickel thin films and nanotubes by using nickelocene as a precursor, water as the oxidant agent and an in-cycle plasma enhanced reduction step with hydrogen. The optimized ALD pulse sequence, combined with a post-processing annealing treatment, allowed us to prepare 30 nm thick metallic Ni layers with a resistivity of 8 μΩcm at room temperature and good conformality both on the planar substrates and nanotemplates. Thereby we fabricated several micrometer-long nickel nanotubes with diameters ranging from 120 to 330 nm. We report on the correlation between ALD growth and functional properties of individual Ni nanotubes characterized in terms of magneto-transport and the confinement of spin wave modes. The findings offer novel perspectives for Ni-based spintronics and magnonic devices operated in the GHz frequency regime with a 3D device architecture.

Raw data associated to the manuscript ‘Efficient wavelength conversion of exchange magnons below 100 nm by magnetic coplanar waveguides.” File formats are described in info.txt files in the concerning folders. For plotting and data evaluation, Python 2.7, Matlab 2018b and OriginPro 2018b were used. We acknowledge the financial support from the Swiss National Science Foundation(SNSF) via sinergia project NanoSkyrmionics CRSII5 171003 and Grant No. 163016 as well as Deutsche Forschungsgemeinschaft via grant DU 1427/2-1. Paper abstract: Exchange magnons are essential for unprecedented miniaturization of GHz electronics and magnon-based logic. However, their efficient excitation via microwave fields is still a challenge. Current methods including nanocontacts and grating couplers require advanced nanofabrication tools which limit the broad usage. Here we report efficient emission and detection of exchange magnons using micron-sized coplanar waveguides (CPWs) into which we integrated ferromagnetic(m) layers. We excited magnons in a broad frequency band with wavelengths λ down to 100 nm propagating over macroscopic distances in thin yttrium iron garnet. Applying time- and spatially resolved Brillouin light scattering as well as micromagnetic simulations we evidence a significant wavelength conversion process near mCPWs via tunable inhomogeneous fields. We argue that optimized mCPWs form microwave-to-magnon transducers providing phase-coherent exchange magnons with down to below 40 nm. Without any nanofabrication they allow one to harvest the advantages of nanomagnonics by antenna designs exploited in conventional microwave circuits.

Raw data associated to the manuscript ‘’Phase control of spin waves based on a magnetic defect in a one-dimensional magnonic crystal‘’, Appl. Phys. Lett. 112, 142405 (2018); doi: 10.1063/1.5024541 File formats are described in info.txt files in the concerning folders. For plotting and data evaluation, Python 2.7 and OriginPro 8.6G were used. Example scrips for plotting are provided. Paper abstract: Magnonic crystals are interesting for spin-wave based data processing. We investigate one-dimensional magnonic crystals (1D MCs) consisting of bistable Co20Fe60B20 nanostripes separated by 75 nm wide air gaps. By adjusting the magnetic history, we program a single stripe of opposed magnetization in an otherwise saturated 1D MC. Its influence on propagating spin waves is studied via broadband microwave spectroscopy. Depending on an in-plane bias magnetic field, we observe spin wave phase shifts of up to almost π and field-controlled attenuation attributed to the reversed nanostripe. Our findings are of importance for magnetologics, where the control of spin wave phases is essential., Funding by SNSF via Grant No.163016