Local probe magnometry of superconductivity in low dimensional pnictidesGosar, Žiga (Avtor) Arčon, Denis (Mentor) nitrogen-vacancy centersuperconductivity$\mathrm{K_2Mo_3As_3}$$\mathrm{Rb_2Mo_3As_3}$$\mathrm{Cs_2Mo_3As_3}$nanodiamondpnictiderelaxometryMaterials from the $\mathrm{A_2Mo_3As_3}$ family where A = K, Rb, or Cs, are investigated using nuclear magnetic resonance (NMR), nuclear quadrupole resonance (NQR) and muon spin spectroscopy ($\mu$SR) techniques. They all show unconventional superconductivity, albeit with different methods showing a different nature of the superconductivity. $^{75}$As NQR on $\mathrm{Cs_2Mo_3As_3}$ shows point-node superconducting gap symmetry. Other methods and samples show gapped behavior, some of them with unusual gap sizes. Above $T_c$, the $^{87}$Rb NMR in $\mathrm{Rb_2Mo_3As_3}$ shows Tomonaga-Luttinger liquid behavior with attractive interactions. Other samples show a conventional Korringa relation indicating a 3D conducting state. $\mu$SR measurements on $\mathrm{Rb_2Mo_3As_3}$ show either $s$-wave superconductivity with a gap smaller than the BCS prediction or $p$-wave symmetry of the superconducting gap with a BCS-sized gap. Similarly, $\mathrm{Cs_2Mo_3As_3}$ measurements also suggest $p$-wave symmetry of the superconducting gap. Additionally, a nitrogen-vacancy center laboratory is established, and its capabilities are demonstrated. Techniques such as optically detected magnetic resonance (ODMR), Rabi oscillations, and longitudinal relaxation rate measurements are demonstrated on bulk diamonds. These techniques are employed to investigate the Johnson noise of a conducting surface using nanodiamonds deposited on that surface. The technique proved to be challenging due to nanodiamond clustering and variability between nanodiamonds.20262026-06-07 08:15:08Doktorsko delo/naloga183194VisID: 160433COBISS_ID: 280809475sl