Two-dimensional metal–organic frameworks (2D MOFs) have attracted much attention, as they are the crystalline materials that exhibit both conductivity and microporosity. Numerous efforts have been made to advance their application as chemiresistive sensors or electrochemical capacitors. However, the intrinsic physical properties and spin states of these materials remain poorly understood. Most of these 2D MOFs possess a honeycomb lattice, with a Kagomé lattice arrangement of metal cations. These structural characteristics suggest that these MOFs would be candidates for geometrically frustrated spin systems with unprecedented magnetic phenomena. Herein, by performing magnetic susceptibility and specific heat measurements at an ultralow temperature down to 38mK on a 2D semiconductive MOF, Cu3(HHTP)2, a quantum spin liquid state that arises from the geometrical frustration was suggested. This result illustrates the potential of strongly correlated MOFs as systems with emergent phenomena induced by unusual structural topologies.

A tunable coplanar resonator using a combination of high-permeability soft magnetic thin film/permanent magnet film was fabricated and evaluated. The magnetic pole based on the remanent magnetization of permanent magnet film, which is controlled by a pulse-current magnetization scheme, generates a dc bias magnetic field in the soft magnetic film. Consequently, the permeability of the soft magnetic film can be controlled by changing the pulse-current magnetization for the permanent magnet film. A scheme to control the permeability of the soft magnetic film is described here, and fabrication and evaluation of the tunable coplanar-resonator are also explained.

In this paper, the authors have proposed a possibility of a magnetic field biasing tunable inductive device. To confirm a new scheme, a tunable coplanar waveguide (CPW) resonator with a combination of soft magnetic thin film and hard magnetic film has been fabricated and evaluated. The magnetic pole of hard magnetic film can be controlled by magnetization using a pulsed magnetic field. A bias magnetic field is applied in the soft magnetic film from the magnetic pole of the hard magnet film. Consequently, permeability of the soft magnetic film can be controlled by changing amplitude of the pulsed magnetic field in the magnetizing for the hard magnetic film. A 20 mm long coplanar wave guide resonator has been fabricated using FeSiO/SiO 2 granular multilayer film and FeCoSm amorphous hard magnetic film. From the experimental results, in case of using 0.2 m thick soft granular film, by changing amplitude of the 1 ms width currentpulse for magnetizing pulsed magnetic field for hard magnetic film, the maximum inductance change was up to 18 %, and maximum change of the resonant frequency was 9.6 %. The control energy for one time tuning was small enough (5.4 Wh).Index Terms-Tunable inductive device, cell phone, hard magnetic film, soft magnetic film, pulsed-current magnetization method.