Millimeter wave notch filters based on ferromagnetic resonance in hexagonal barium ferrites

Abstract

A hexagonal ferrite-based millimeter wave notch filter was demonstrated. The filter consists of an M-type BaFe12O19 (BaM) slab sitting on top of a stripline. The band-stop filtering response originates from the ferromagnetic resonance absorption in the BaM slab. The BaM slab has an in-plane uniaxial anisotropy field of 17 kOe. This anisotropy field facilitates the operation of the filter beyond 50 GHz without a need of high external fields. The operating frequency increases linearly with the external field, while the bandwidth versus field profile shows a U-shaped response. The physical mechanisms for these responses were discussed.

Structural and millimeter-wave characterization of flux grown Al substituted barium hexaferrite single crystals

“…Hexagonal ferrites with large magnetocrystalline anisotropy are promising for mm-wave applications as well as for use in sub-terahertz range. In particular, tunable resonators [17][18][19][20][21], isolators [22] and radio-absorbing coatings [13] were developed with the use of films or bulk hexaferrite materials. In this context the elaboration of a robust technology for production of hexaferrite single crystals became important in recent years [23][24][25].…”

M-Type Barium Hexagonal Ferrite Films

“…10,[18][19][20][21][22][23][24] Such devices include (1) notch filters made of BaM thin films and microstrip geometry, (2) notch filters made of BaM slabs and strip-line geometry, (3) selfbiased notch filters using high-M r BaM thin films and coplanar waveguide (CPW) geometry, (4) notch filters based on the excitation of confined magnetostatic waves in narrow BaM strips and CPW configurations, and (5) phase shifters using BaM thin films and CPW geometry. This section describes the device configurations and responses of (3), (4), and (5).…”

“…16,17 The device demonstration includes both numerical 20,21,22 and experimental efforts. 18,21,22,23,10,24 The devices demonstrated include phase shifters, 21 filters, 22,23,10 ,24 circulators, 18 and isolators. 19 This chapter reviews the main advances made in the field of BaM materials and devices over the past five years.…”

“…Emphasis has been placed on the optimization of deposition processes for low-loss, self-biased BaM thin films, 7,8,9,10 the deposition of BaM thin films on "non-conventional" substrates, such as semiconductor substrates 11,12,13,14 and metallic substrates, 15 the fabrication of BaM thick films on semiconductor substrates, 16,17 the demonstration of BaM-based planar mm-wave devices, 18,19,20,21,22,23,10,24 the development of BaM-based ferromagnetic/ferroelectric heterostructures, 25,26,27,28,29 and the study of multiferroic effects in single-phase BaM materials. 30 A variety of different techniques have been used to fabricate BaM film materials.…”

Proximity effect between a topological insulator and a magnetic insulator with large perpendicular anisotropy

“…21 Thus far, strong proximity effect between a TI and an MI with perpendicular anisotropy has not yet been reported, even though strong interface interaction has been realized recently in a TI/magnetically doped TI heterostructure. 22 Here we demonstrate that Bi 2 Se 3 thin films can be epitaxially grown onto BaFe 12 [23][24][25][26][27] It is highly insulating and has a Curie temperature of 723 K. 27 In this work, the flat (0001) surfaces of nearly hexagon-shaped single crystalline thin plates (Fig. 1a), were used as the substrates for epitaxial growth of Bi 2 Se 3 thin films.…”