Ferromagnetic resonance study of sputtered Co|Ni multilayers

We report on room temperature ferromagnetic resonance (FMR) studies of [$t$ Co$|2t$ Ni]$\times$N sputtered films, where $0.1 \leq t \leq 0.6$ nm. Two series of films were investigated: films with same number of Co$|$Ni bilayer repeats (N=12), and samples in which the overall magnetic layer thickness is kept constant at 3.6 nm (N=1.2/$t$). The FMR measurements were conducted with a high frequency broadband coplanar waveguide up to 50 GHz using a flip-chip method. The resonance field and the full width at half maximum were measured as a function of frequency for the field in-plane and field normal to the plane, and as a function of angle to the plane for several frequencies. For both sets of films, we find evidence for the presence of first and second order anisotropy constants, $K_1$ and $K_2$. The anisotropy constants are strongly dependent on the thickness $t$, and to a lesser extent on the total thickness of the magnetic multilayer. The Land\'e g-factor increases with decreasing $t$ and is practically independent of the multilayer thickness. The magnetic damping parameter $\alpha$, estimated from the linear dependence of the linewidth, $\triangle H$, on frequency, in the field in-plane geometry, increases with decreasing $t$. This behaviour is attributed to an enhancement of spin-orbit interactions with $t$ decreasing and in thinner films, to a spin-pumping contribution to the damping.Comment: 18 pages, 13 figure

Quantum Physics and Human Language

Human languages employ constructions that tacitly assume specific properties of the limited range of phenomena they evolved to describe. These assumed properties are true features of that limited context, but may not be general or precise properties of all the physical situations allowed by fundamental physics. In brief, human languages contain `excess baggage' that must be qualified, discarded, or otherwise reformed to give a clear account in the context of fundamental physics of even the everyday phenomena that the languages evolved to describe. The surest route to clarity is to express the constructions of human languages in the language of fundamental physical theory, not the other way around. These ideas are illustrated by an analysis of the verb `to happen' and the word `reality' in special relativity and the modern quantum mechanics of closed systems.Comment: Contribution to the festschrift for G.C. Ghirardi on his 70th Birthday, minor correction

Internet-based search of randomised trials relevant to mental health originating in the Arab world

BACKGROUND: The internet is becoming a widely used source of accessing medical research through various on-line databases. This instant access to information is of benefit to busy clinicians and service users around the world. The population of the Arab World is comparable to that of the United States, yet it is widely believed to have a greatly contrasting output of randomised controlled trials related to mental health. This study was designed to investigate the existence of such research in the Arab World and also to investigate the availability of this research on-line. METHODS: Survey of findings from three internet-based potential sources of randomised trials originating from the Arab world and relevant to mental health care. RESULTS: A manual search of an Arabic online current contents service identified 3 studies, MEDLINE, EMBASE, and PsycINFO searches identified only 1 study, and a manual search of a specifically indexed, study-based mental health database, PsiTri, revealed 27 trials. CONCLUSION: There genuinely seem to be few trials from the Arab world and accessing these on-line was problematic. Replication of some studies that guide psychiatric/psychological practice in the Arab world would seem prudent