You need three components in total, lets say my third component studysMainCmp and is as below.

<aura:component access="global" implements="force:appHostable">
    <aura:handler name="init" value="{!this}" action="{!c.doInit}" />
    <aura:handler event="c:navigateToCmp" action="{!c.NavigateComponent}" />

    <div>
        {!v.body}
    </div>
</aura:component>

Controller:

doInit : function(component, event, helper) {
    $A.createComponent("c:studys", {

    }, function(newCmp) {
        if (component.isValid()) {
            component.set("v.body", newCmp);
        }
    });
},

NavigateComponent : function(component, event, helper) {
if(event.getParam("navigate") == "true")
{
    $A.createComponent("c:studyDetail", {

        }, function(newCmp) {
            if (component.isValid()) {
                component.set("v.body", newCmp);
            }
        });
}
}

In your study component the button action should fire an event, the button function will be as below

buttonFunction : function(component, event) {
    var event = $A.get("e.c:navigateToCmp");
    event.setParams({
        "navigate" : "true"
    });
    event.fire();
},

Lightning event named navigateToCmp will be as below:

<aura:event access="global" type="APPLICATION" description="Event template" >
    <aura:attribute name="navigate" type="Boolean" default="false"/>
</aura:event>